Call `OpenSSL_add_all_algorithms()` on older openssl versions.

[rsync.git] / rsync.1.md

## NAME

rsync - a fast, versatile, remote (and local) file-copying tool

## SYNOPSIS

```
Local:
    rsync [OPTION...] SRC... [DEST]

Access via remote shell:
    Pull:
        rsync [OPTION...] [USER@]HOST:SRC... [DEST]
    Push:
        rsync [OPTION...] SRC... [USER@]HOST:DEST

Access via rsync daemon:
    Pull:
        rsync [OPTION...] [USER@]HOST::SRC... [DEST]
        rsync [OPTION...] rsync://[USER@]HOST[:PORT]/SRC... [DEST]
    Push:
        rsync [OPTION...] SRC... [USER@]HOST::DEST
        rsync [OPTION...] SRC... rsync://[USER@]HOST[:PORT]/DEST)
```

Usages with just one SRC arg and no DEST arg will list the source files instead
of copying.

The online version of this manpage (that includes cross-linking of topics)
is available at <https://download.samba.org/pub/rsync/rsync.1>.

## DESCRIPTION

Rsync is a fast and extraordinarily versatile file copying tool.  It can copy
locally, to/from another host over any remote shell, or to/from a remote rsync
daemon.  It offers a large number of options that control every aspect of its
behavior and permit very flexible specification of the set of files to be
copied.  It is famous for its delta-transfer algorithm, which reduces the
amount of data sent over the network by sending only the differences between
the source files and the existing files in the destination.  Rsync is widely
used for backups and mirroring and as an improved copy command for everyday
use.

Rsync finds files that need to be transferred using a "quick check" algorithm
(by default) that looks for files that have changed in size or in last-modified
time.  Any changes in the other preserved attributes (as requested by options)
are made on the destination file directly when the quick check indicates that
the file's data does not need to be updated.

Some of the additional features of rsync are:

- support for copying links, devices, owners, groups, and permissions
- exclude and exclude-from options similar to GNU tar
- a CVS exclude mode for ignoring the same files that CVS would ignore
- can use any transparent remote shell, including ssh or rsh
- does not require super-user privileges
- pipelining of file transfers to minimize latency costs
- support for anonymous or authenticated rsync daemons (ideal for mirroring)

## GENERAL

Rsync copies files either to or from a remote host, or locally on the current
host (it does not support copying files between two remote hosts).

There are two different ways for rsync to contact a remote system: using a
remote-shell program as the transport (such as ssh or rsh) or contacting an
rsync daemon directly via TCP.  The remote-shell transport is used whenever the
source or destination path contains a single colon (:) separator after a host
specification.  Contacting an rsync daemon directly happens when the source or
destination path contains a double colon (::) separator after a host
specification, OR when an rsync:// URL is specified (see also the [USING
RSYNC-DAEMON FEATURES VIA A REMOTE-SHELL CONNECTION](#) section for an
exception to this latter rule).

As a special case, if a single source arg is specified without a destination,
the files are listed in an output format similar to "`ls -l`".

As expected, if neither the source or destination path specify a remote host,
the copy occurs locally (see also the [`--list-only`](#opt) option).

Rsync refers to the local side as the client and the remote side as the server.
Don't confuse server with an rsync daemon.  A daemon is always a server, but a
server can be either a daemon or a remote-shell spawned process.

## SETUP

See the file README.md for installation instructions.

Once installed, you can use rsync to any machine that you can access via a
remote shell (as well as some that you can access using the rsync daemon-mode
protocol).  For remote transfers, a modern rsync uses ssh for its
communications, but it may have been configured to use a different remote shell
by default, such as rsh or remsh.

You can also specify any remote shell you like, either by using the [`-e`](#opt)
command line option, or by setting the [`RSYNC_RSH`](#) environment variable.

Note that rsync must be installed on both the source and destination machines.

## USAGE

You use rsync in the same way you use rcp.  You must specify a source and a
destination, one of which may be remote.

Perhaps the best way to explain the syntax is with some examples:

>     rsync -t *.c foo:src/

This would transfer all files matching the pattern `*.c` from the current
directory to the directory src on the machine foo.  If any of the files already
exist on the remote system then the rsync remote-update protocol is used to
update the file by sending only the differences in the data.  Note that the
expansion of wildcards on the command-line (`*.c`) into a list of files is
handled by the shell before it runs rsync and not by rsync itself (exactly the
same as all other Posix-style programs).

>     rsync -avz foo:src/bar /data/tmp

This would recursively transfer all files from the directory src/bar on the
machine foo into the /data/tmp/bar directory on the local machine.  The files
are transferred in archive mode, which ensures that symbolic links, devices,
attributes, permissions, ownerships, etc. are preserved in the transfer.
Additionally, compression will be used to reduce the size of data portions of
the transfer.

>     rsync -avz foo:src/bar/ /data/tmp

A trailing slash on the source changes this behavior to avoid creating an
additional directory level at the destination.  You can think of a trailing /
on a source as meaning "copy the contents of this directory" as opposed to
"copy the directory by name", but in both cases the attributes of the
containing directory are transferred to the containing directory on the
destination.  In other words, each of the following commands copies the files
in the same way, including their setting of the attributes of /dest/foo:

>     rsync -av /src/foo /dest
>     rsync -av /src/foo/ /dest/foo

Note also that host and module references don't require a trailing slash to
copy the contents of the default directory.  For example, both of these copy
the remote directory's contents into "/dest":

>     rsync -av host: /dest
>     rsync -av host::module /dest

You can also use rsync in local-only mode, where both the source and
destination don't have a ':' in the name.  In this case it behaves like an
improved copy command.

Finally, you can list all the (listable) modules available from a particular
rsync daemon by leaving off the module name:

>     rsync somehost.mydomain.com::

## COPYING TO A DIFFERENT NAME

When you want to copy a directory to a different name, use a trailing slash on
the source directory to put the contents of the directory into any destination
directory you like:

>     rsync -ai foo/ bar/

Rsync also has the ability to customize a destination file's name when copying
a single item.  The rules for this are:

- The transfer list must consist of a single item (either a file or an empty
  directory)
- The final element of the destination path must not exist as a directory
- The destination path must not have been specified with a trailing slash

Under those circumstances, rsync will set the name of the destination's single
item to the last element of the destination path.  Keep in mind that it is best
to only use this idiom when copying a file and use the above trailing-slash
idiom when copying a directory.

The following example copies the `foo.c` file as `bar.c` in the `save` dir
(assuming that `bar.c` isn't a directory):

>     rsync -ai src/foo.c save/bar.c

The single-item copy rule might accidentally bite you if you unknowingly copy a
single item and specify a destination dir that doesn't exist (without using a
trailing slash).  For example, if `src/*.c` matches one file and `save/dir`
doesn't exist, this will confuse you by naming the destination file `save/dir`:

>     rsync -ai src/*.c save/dir

To prevent such an accident, either make sure the destination dir exists or
specify the destination path with a trailing slash:

>     rsync -ai src/*.c save/dir/

## SORTED TRANSFER ORDER

Rsync always sorts the specified filenames into its internal transfer list.
This handles the merging together of the contents of identically named
directories, makes it easy to remove duplicate filenames. It can, however,
confuse someone when the files are transferred in a different order than what
was given on the command-line.

If you need a particular file to be transferred prior to another, either
separate the files into different rsync calls, or consider using
[`--delay-updates`](#opt) (which doesn't affect the sorted transfer order, but
does make the final file-updating phase happen much more rapidly).

## MULTI-HOST SECURITY

Rsync takes steps to ensure that the file requests that are shared in a
transfer are protected against various security issues.  Most of the potential
problems arise on the receiving side where rsync takes steps to ensure that the
list of files being transferred remains within the bounds of what was
requested.

Toward this end, rsync 3.1.2 and later have aborted when a file list contains
an absolute or relative path that tries to escape out of the top of the
transfer.  Also, beginning with version 3.2.5, rsync does two more safety
checks of the file list to (1) ensure that no extra source arguments were added
into the transfer other than those that the client requested and (2) ensure
that the file list obeys the exclude rules that were sent to the sender.

For those that don't yet have a 3.2.5 client rsync (or those that want to be
extra careful), it is safest to do a copy into a dedicated destination
directory for the remote files when you don't trust the remote host.  For
example, instead of doing an rsync copy into your home directory:

>     rsync -aiv host1:dir1 ~

Dedicate a "host1-files" dir to the remote content:

>     rsync -aiv host1:dir1 ~/host1-files

See the [`--trust-sender`](#opt) option for additional details.

CAUTION: it is not particularly safe to use rsync to copy files from a
case-preserving filesystem to a case-ignoring filesystem.  If you must perform
such a copy, you should either disable symlinks via `--no-links` or enable the
munging of symlinks via [`--munge-links`](#opt) (and make sure you use the
right local or remote option).  This will prevent rsync from doing potentially
dangerous things if a symlink name overlaps with a file or directory. It does
not, however, ensure that you get a full copy of all the files (since that may
not be possible when the names overlap). A potentially better solution is to
list all the source files and create a safe list of filenames that you pass to
the [`--files-from`](#opt) option.  Any files that conflict in name would need
to be copied to different destination directories using more than one copy.

While a copy of a case-ignoring filesystem to a case-ignoring filesystem can
work out fairly well, if no `--delete-during` or `--delete-before` option is
active, rsync can potentially update an existing file on the receiveing side
without noticing that the upper-/lower-case of the filename should be changed
to match the sender.

## ADVANCED USAGE

The syntax for requesting multiple files from a remote host is done by
specifying additional remote-host args in the same style as the first, or with
the hostname omitted.  For instance, all these work:

>     rsync -aiv host:file1 :file2 host:file{3,4} /dest/
>     rsync -aiv host::modname/file{1,2} host::modname/extra /dest/
>     rsync -aiv host::modname/first ::extra-file{1,2} /dest/

Note that a daemon connection only supports accessing one module per copy
command, so if the start of a follow-up path doesn't begin with the
modname of the first path, it is assumed to be a path in the module (such as
the extra-file1 & extra-file2 that are grabbed above).

Really old versions of rsync (2.6.9 and before) only allowed specifying one
remote-source arg, so some people have instead relied on the remote-shell
performing space splitting to break up an arg into multiple paths. Such
unintuitive behavior is no longer supported by default (though you can request
it, as described below).

Starting in 3.2.4, filenames are passed to a remote shell in such a way as to
preserve the characters you give it. Thus, if you ask for a file with spaces
in the name, that's what the remote rsync looks for:

>     rsync -aiv host:'a simple file.pdf' /dest/

If you use scripts that have been written to manually apply extra quoting to
the remote rsync args (or to require remote arg splitting), you can ask rsync
to let your script handle the extra escaping.  This is done by either adding
the [`--old-args`](#opt) option to the rsync runs in the script (which requires
a new rsync) or exporting [RSYNC_OLD_ARGS](#)=1 and [RSYNC_PROTECT_ARGS](#)=0
(which works with old or new rsync versions).

## CONNECTING TO AN RSYNC DAEMON

It is also possible to use rsync without a remote shell as the transport.  In
this case you will directly connect to a remote rsync daemon, typically using
TCP port 873. (This obviously requires the daemon to be running on the remote
system, so refer to the [STARTING AN RSYNC DAEMON TO ACCEPT CONNECTIONS](#)
section below for information on that.)

Using rsync in this way is the same as using it with a remote shell except
that:

- Use either double-colon syntax or rsync:// URL syntax instead of the
  single-colon (remote shell) syntax.
- The first element of the "path" is actually a module name.
- Additional remote source args can use an abbreviated syntax that omits the
  hostname and/or the module name, as discussed in [ADVANCED USAGE](#).
- The remote daemon may print a "message of the day" when you connect.
- If you specify only the host (with no module or path) then a list of
  accessible modules on the daemon is output.
- If you specify a remote source path but no destination, a listing of the
  matching files on the remote daemon is output.
- The [`--rsh`](#opt) (`-e`) option must be omitted to avoid changing the
  connection style from using a socket connection to [USING RSYNC-DAEMON
  FEATURES VIA A REMOTE-SHELL CONNECTION](#).

An example that copies all the files in a remote module named "src":

>     rsync -av host::src /dest

Some modules on the remote daemon may require authentication.  If so, you will
receive a password prompt when you connect.  You can avoid the password prompt
by setting the environment variable [`RSYNC_PASSWORD`](#) to the password you
want to use or using the [`--password-file`](#opt) option.  This may be useful
when scripting rsync.

WARNING: On some systems environment variables are visible to all users.  On
those systems using [`--password-file`](#opt) is recommended.

You may establish the connection via a web proxy by setting the environment
variable [`RSYNC_PROXY`](#) to a hostname:port pair pointing to your web proxy.
Note that your web proxy's configuration must support proxy connections to port
873.

You may also establish a daemon connection using a program as a proxy by
setting the environment variable [`RSYNC_CONNECT_PROG`](#) to the commands you
wish to run in place of making a direct socket connection.  The string may
contain the escape "%H" to represent the hostname specified in the rsync
command (so use "%%" if you need a single "%" in your string).  For example:

>     export RSYNC_CONNECT_PROG='ssh proxyhost nc %H 873'
>     rsync -av targethost1::module/src/ /dest/
>     rsync -av rsync://targethost2/module/src/ /dest/

The command specified above uses ssh to run nc (netcat) on a proxyhost, which
forwards all data to port 873 (the rsync daemon) on the targethost (%H).

Note also that if the [`RSYNC_SHELL`](#) environment variable is set, that
program will be used to run the `RSYNC_CONNECT_PROG` command instead of using
the default shell of the **system()** call.

## USING RSYNC-DAEMON FEATURES VIA A REMOTE-SHELL CONNECTION

It is sometimes useful to use various features of an rsync daemon (such as
named modules) without actually allowing any new socket connections into a
system (other than what is already required to allow remote-shell access).
Rsync supports connecting to a host using a remote shell and then spawning a
single-use "daemon" server that expects to read its config file in the home dir
of the remote user.  This can be useful if you want to encrypt a daemon-style
transfer's data, but since the daemon is started up fresh by the remote user,
you may not be able to use features such as chroot or change the uid used by
the daemon. (For another way to encrypt a daemon transfer, consider using ssh
to tunnel a local port to a remote machine and configure a normal rsync daemon
on that remote host to only allow connections from "localhost".)

From the user's perspective, a daemon transfer via a remote-shell connection
uses nearly the same command-line syntax as a normal rsync-daemon transfer,
with the only exception being that you must explicitly set the remote shell
program on the command-line with the [`--rsh=COMMAND`](#opt) option. (Setting the
RSYNC_RSH in the environment will not turn on this functionality.) For example:

>     rsync -av --rsh=ssh host::module /dest

If you need to specify a different remote-shell user, keep in mind that the
user@ prefix in front of the host is specifying the rsync-user value (for a
module that requires user-based authentication).  This means that you must give
the '-l user' option to ssh when specifying the remote-shell, as in this
example that uses the short version of the [`--rsh`](#opt) option:

>     rsync -av -e "ssh -l ssh-user" rsync-user@host::module /dest

The "ssh-user" will be used at the ssh level; the "rsync-user" will be used to
log-in to the "module".

In this setup, the daemon is started by the ssh command that is accessing the
system (which can be forced via the `~/.ssh/authorized_keys` file, if desired).
However, when accessing a daemon directly, it needs to be started beforehand.

## STARTING AN RSYNC DAEMON TO ACCEPT CONNECTIONS

In order to connect to an rsync daemon, the remote system needs to have a
daemon already running (or it needs to have configured something like inetd to
spawn an rsync daemon for incoming connections on a particular port).  For full
information on how to start a daemon that will handling incoming socket
connections, see the [**rsyncd.conf**(5)](rsyncd.conf.5) manpage -- that is
the config file for the daemon, and it contains the full details for how to run
the daemon (including stand-alone and inetd configurations).

If you're using one of the remote-shell transports for the transfer, there is
no need to manually start an rsync daemon.

## EXAMPLES

Here are some examples of how rsync can be used.

To backup a home directory, which consists of large MS Word files and mail
folders, a per-user cron job can be used that runs this each day:

>     rsync -aiz . bkhost:backup/joe/

To move some files from a remote host to the local host, you could run:

>     rsync -aiv --remove-source-files rhost:/tmp/{file1,file2}.c ~/src/

## OPTION SUMMARY

Here is a short summary of the options available in rsync.  Each option also
has its own detailed description later in this manpage.

[comment]: # (help-rsync.h)
[comment]: # (Keep these short enough that they'll be under 80 chars when indented by 7 chars.)

```
--verbose, -v            increase verbosity
--info=FLAGS             fine-grained informational verbosity
--debug=FLAGS            fine-grained debug verbosity
--stderr=e|a|c           change stderr output mode (default: errors)
--quiet, -q              suppress non-error messages
--no-motd                suppress daemon-mode MOTD
--checksum, -c           skip based on checksum, not mod-time & size
--archive, -a            archive mode is -rlptgoD (no -A,-X,-U,-N,-H)
--no-OPTION              turn off an implied OPTION (e.g. --no-D)
--recursive, -r          recurse into directories
--relative, -R           use relative path names
--no-implied-dirs        don't send implied dirs with --relative
--backup, -b             make backups (see --suffix & --backup-dir)
--backup-dir=DIR         make backups into hierarchy based in DIR
--suffix=SUFFIX          backup suffix (default ~ w/o --backup-dir)
--update, -u             skip files that are newer on the receiver
--inplace                update destination files in-place
--append                 append data onto shorter files
--append-verify          --append w/old data in file checksum
--dirs, -d               transfer directories without recursing
--old-dirs, --old-d      works like --dirs when talking to old rsync
--mkpath                 create destination's missing path components
--links, -l              copy symlinks as symlinks
--copy-links, -L         transform symlink into referent file/dir
--copy-unsafe-links      only "unsafe" symlinks are transformed
--safe-links             ignore symlinks that point outside the tree
--munge-links            munge symlinks to make them safe & unusable
--copy-dirlinks, -k      transform symlink to dir into referent dir
--keep-dirlinks, -K      treat symlinked dir on receiver as dir
--hard-links, -H         preserve hard links
--perms, -p              preserve permissions
--executability, -E      preserve executability
--chmod=CHMOD            affect file and/or directory permissions
--acls, -A               preserve ACLs (implies --perms)
--xattrs, -X             preserve extended attributes
--owner, -o              preserve owner (super-user only)
--group, -g              preserve group
--devices                preserve device files (super-user only)
--copy-devices           copy device contents as a regular file
--write-devices          write to devices as files (implies --inplace)
--specials               preserve special files
-D                       same as --devices --specials
--times, -t              preserve modification times
--atimes, -U             preserve access (use) times
--open-noatime           avoid changing the atime on opened files
--crtimes, -N            preserve create times (newness)
--omit-dir-times, -O     omit directories from --times
--omit-link-times, -J    omit symlinks from --times
--super                  receiver attempts super-user activities
--fake-super             store/recover privileged attrs using xattrs
--sparse, -S             turn sequences of nulls into sparse blocks
--preallocate            allocate dest files before writing them
--dry-run, -n            perform a trial run with no changes made
--whole-file, -W         copy files whole (w/o delta-xfer algorithm)
--checksum-choice=STR    choose the checksum algorithm (aka --cc)
--one-file-system, -x    don't cross filesystem boundaries
--block-size=SIZE, -B    force a fixed checksum block-size
--rsh=COMMAND, -e        specify the remote shell to use
--rsync-path=PROGRAM     specify the rsync to run on remote machine
--existing               skip creating new files on receiver
--ignore-existing        skip updating files that exist on receiver
--remove-source-files    sender removes synchronized files (non-dir)
--del                    an alias for --delete-during
--delete                 delete extraneous files from dest dirs
--delete-before          receiver deletes before xfer, not during
--delete-during          receiver deletes during the transfer
--delete-delay           find deletions during, delete after
--delete-after           receiver deletes after transfer, not during
--delete-excluded        also delete excluded files from dest dirs
--ignore-missing-args    ignore missing source args without error
--delete-missing-args    delete missing source args from destination
--ignore-errors          delete even if there are I/O errors
--force                  force deletion of dirs even if not empty
--max-delete=NUM         don't delete more than NUM files
--max-size=SIZE          don't transfer any file larger than SIZE
--min-size=SIZE          don't transfer any file smaller than SIZE
--max-alloc=SIZE         change a limit relating to memory alloc
--partial                keep partially transferred files
--partial-dir=DIR        put a partially transferred file into DIR
--delay-updates          put all updated files into place at end
--prune-empty-dirs, -m   prune empty directory chains from file-list
--numeric-ids            don't map uid/gid values by user/group name
--usermap=STRING         custom username mapping
--groupmap=STRING        custom groupname mapping
--chown=USER:GROUP       simple username/groupname mapping
--timeout=SECONDS        set I/O timeout in seconds
--contimeout=SECONDS     set daemon connection timeout in seconds
--ignore-times, -I       don't skip files that match size and time
--size-only              skip files that match in size
--modify-window=NUM, -@  set the accuracy for mod-time comparisons
--temp-dir=DIR, -T       create temporary files in directory DIR
--fuzzy, -y              find similar file for basis if no dest file
--compare-dest=DIR       also compare destination files relative to DIR
--copy-dest=DIR          ... and include copies of unchanged files
--link-dest=DIR          hardlink to files in DIR when unchanged
--compress, -z           compress file data during the transfer
--compress-choice=STR    choose the compression algorithm (aka --zc)
--compress-level=NUM     explicitly set compression level (aka --zl)
--skip-compress=LIST     skip compressing files with suffix in LIST
--cvs-exclude, -C        auto-ignore files in the same way CVS does
--filter=RULE, -f        add a file-filtering RULE
-F                       same as --filter='dir-merge /.rsync-filter'
                         repeated: --filter='- .rsync-filter'
--exclude=PATTERN        exclude files matching PATTERN
--exclude-from=FILE      read exclude patterns from FILE
--include=PATTERN        don't exclude files matching PATTERN
--include-from=FILE      read include patterns from FILE
--files-from=FILE        read list of source-file names from FILE
--from0, -0              all *-from/filter files are delimited by 0s
--old-args               disable the modern arg-protection idiom
--secluded-args, -s      use the protocol to safely send the args
--trust-sender           trust the remote sender's file list
--copy-as=USER[:GROUP]   specify user & optional group for the copy
--address=ADDRESS        bind address for outgoing socket to daemon
--port=PORT              specify double-colon alternate port number
--sockopts=OPTIONS       specify custom TCP options
--blocking-io            use blocking I/O for the remote shell
--outbuf=N|L|B           set out buffering to None, Line, or Block
--stats                  give some file-transfer stats
--8-bit-output, -8       leave high-bit chars unescaped in output
--human-readable, -h     output numbers in a human-readable format
--progress               show progress during transfer
-P                       same as --partial --progress
--itemize-changes, -i    output a change-summary for all updates
--remote-option=OPT, -M  send OPTION to the remote side only
--out-format=FORMAT      output updates using the specified FORMAT
--log-file=FILE          log what we're doing to the specified FILE
--log-file-format=FMT    log updates using the specified FMT
--password-file=FILE     read daemon-access password from FILE
--early-input=FILE       use FILE for daemon's early exec input
--list-only              list the files instead of copying them
--bwlimit=RATE           limit socket I/O bandwidth
--stop-after=MINS        Stop rsync after MINS minutes have elapsed
--stop-at=y-m-dTh:m      Stop rsync at the specified point in time
--fsync                  fsync every written file
--write-batch=FILE       write a batched update to FILE
--only-write-batch=FILE  like --write-batch but w/o updating dest
--read-batch=FILE        read a batched update from FILE
--protocol=NUM           force an older protocol version to be used
--iconv=CONVERT_SPEC     request charset conversion of filenames
--checksum-seed=NUM      set block/file checksum seed (advanced)
--ipv4, -4               prefer IPv4
--ipv6, -6               prefer IPv6
--version, -V            print the version + other info and exit
--help, -h (*)           show this help (* -h is help only on its own)
```

Rsync can also be run as a daemon, in which case the following options are
accepted:

[comment]: # (help-rsyncd.h)

```
--daemon                 run as an rsync daemon
--address=ADDRESS        bind to the specified address
--bwlimit=RATE           limit socket I/O bandwidth
--config=FILE            specify alternate rsyncd.conf file
--dparam=OVERRIDE, -M    override global daemon config parameter
--no-detach              do not detach from the parent
--port=PORT              listen on alternate port number
--log-file=FILE          override the "log file" setting
--log-file-format=FMT    override the "log format" setting
--sockopts=OPTIONS       specify custom TCP options
--verbose, -v            increase verbosity
--ipv4, -4               prefer IPv4
--ipv6, -6               prefer IPv6
--help, -h               show this help (when used with --daemon)
```

## OPTIONS

Rsync accepts both long (double-dash + word) and short (single-dash + letter)
options.  The full list of the available options are described below.  If an
option can be specified in more than one way, the choices are comma-separated.
Some options only have a long variant, not a short.

If the option takes a parameter, the parameter is only listed after the long
variant, even though it must also be specified for the short.  When specifying
a parameter, you can either use the form `--option=param`, `--option param`,
`-o=param`, `-o param`, or `-oparam` (the latter choices assume that your
option has a short variant).

The parameter may need to be quoted in some manner for it to survive the
shell's command-line parsing.  Also keep in mind that a leading tilde (`~`) in
a pathname is substituted by your shell, so make sure that you separate the
option name from the pathname using a space if you want the local shell to
expand it.

[comment]: # (Some markup below uses a literal non-breakable space when a backtick string)
[comment]: # (needs to contain a space since markdown strips spaces from the start/end)

[comment]: # (An OL starting at 0 is converted into a DL by the parser.)

0.  `--help`

    Print a short help page describing the options available in rsync and exit.
    You can also use `-h` for `--help` when it is used without any other
    options (since it normally means [`--human-readable`](#opt)).

0.  `--version`, `-V`

    Print the rsync version plus other info and exit.  When repeated, the
    information is output is a JSON format that is still fairly readable
    (client side only).

    The output includes a list of compiled-in capabilities, a list of
    optimizations, the default list of checksum algorithms, the default list of
    compression algorithms, the default list of daemon auth digests, a link to
    the rsync web site, and a few other items.

0.  `--verbose`, `-v`

    This option increases the amount of information you are given during the
    transfer.  By default, rsync works silently.  A single `-v` will give you
    information about what files are being transferred and a brief summary at
    the end.  Two `-v` options will give you information on what files are
    being skipped and slightly more information at the end.  More than two `-v`
    options should only be used if you are debugging rsync.

    The end-of-run summary tells you the number of bytes sent to the remote
    rsync (which is the receiving side on a local copy), the number of bytes
    received from the remote host, and the average bytes per second of the
    transferred data computed over the entire length of the rsync run. The
    second line shows the total size (in bytes), which is the sum of all the
    file sizes that rsync considered transferring.  It also shows a "speedup"
    value, which is a ratio of the total file size divided by the sum of the
    sent and received bytes (which is really just a feel-good bigger-is-better
    number).  Note that these byte values can be made more (or less)
    human-readable by using the [`--human-readable`](#opt) (or
    `--no-human-readable`) options.

    In a modern rsync, the `-v` option is equivalent to the setting of groups
    of [`--info`](#opt) and [`--debug`](#opt) options.  You can choose to use
    these newer options in addition to, or in place of using `--verbose`, as
    any fine-grained settings override the implied settings of `-v`.  Both
    [`--info`](#opt) and [`--debug`](#opt) have a way to ask for help that
    tells you exactly what flags are set for each increase in verbosity.

    However, do keep in mind that a daemon's "`max verbosity`" setting will limit
    how high of a level the various individual flags can be set on the daemon
    side.  For instance, if the max is 2, then any info and/or debug flag that
    is set to a higher value than what would be set by `-vv` will be downgraded
    to the `-vv` level in the daemon's logging.

0.  `--info=FLAGS`

    This option lets you have fine-grained control over the information output
    you want to see.  An individual flag name may be followed by a level
    number, with 0 meaning to silence that output, 1 being the default output
    level, and higher numbers increasing the output of that flag (for those
    that support higher levels).  Use `--info=help` to see all the available
    flag names, what they output, and what flag names are added for each
    increase in the verbose level.  Some examples:

    >     rsync -a --info=progress2 src/ dest/
    >     rsync -avv --info=stats2,misc1,flist0 src/ dest/

    Note that `--info=name`'s output is affected by the [`--out-format`](#opt)
    and [`--itemize-changes`](#opt) (`-i`) options.  See those options for more
    information on what is output and when.

    This option was added to 3.1.0, so an older rsync on the server side might
    reject your attempts at fine-grained control (if one or more flags needed
    to be send to the server and the server was too old to understand them).
    See also the "`max verbosity`" caveat above when dealing with a daemon.

0.  `--debug=FLAGS`

    This option lets you have fine-grained control over the debug output you
    want to see.  An individual flag name may be followed by a level number,
    with 0 meaning to silence that output, 1 being the default output level,
    and higher numbers increasing the output of that flag (for those that
    support higher levels).  Use `--debug=help` to see all the available flag
    names, what they output, and what flag names are added for each increase in
    the verbose level.  Some examples:

    >     rsync -avvv --debug=none src/ dest/
    >     rsync -avA --del --debug=del2,acl src/ dest/

    Note that some debug messages will only be output when the [`--stderr=all`](#opt)
    option is specified, especially those pertaining to I/O and buffer debugging.

    Beginning in 3.2.0, this option is no longer auto-forwarded to the server
    side in order to allow you to specify different debug values for each side
    of the transfer, as well as to specify a new debug option that is only
    present in one of the rsync versions.  If you want to duplicate the same
    option on both sides, using brace expansion is an easy way to save you some
    typing.  This works in zsh and bash:

    >     rsync -aiv {-M,}--debug=del2 src/ dest/

0.  `--stderr=errors|all|client`

    This option controls which processes output to stderr and if info messages
    are also changed to stderr.  The mode strings can be abbreviated, so feel
    free to use a single letter value.  The 3 possible choices are:

    - `errors` - (the default) causes all the rsync processes to send an
      error directly to stderr, even if the process is on the remote side of
      the transfer.  Info messages are sent to the client side via the protocol
      stream.  If stderr is not available (i.e. when directly connecting with a
      daemon via a socket) errors fall back to being sent via the protocol
      stream.

    - `all` - causes all rsync messages (info and error) to get written
      directly to stderr from all (possible) processes.  This causes stderr to
      become line-buffered (instead of raw) and eliminates the ability to
      divide up the info and error messages by file handle.  For those doing
      debugging or using several levels of verbosity, this option can help to
      avoid clogging up the transfer stream (which should prevent any chance of
      a deadlock bug hanging things up).  It also allows [`--debug`](#opt) to
      enable some extra I/O related messages.

    - `client` - causes all rsync messages to be sent to the client side
      via the protocol stream.  One client process outputs all messages, with
      errors on stderr and info messages on stdout.  This **was** the default
      in older rsync versions, but can cause error delays when a lot of
      transfer data is ahead of the messages.  If you're pushing files to an
      older rsync, you may want to use `--stderr=all` since that idiom has
      been around for several releases.

    This option was added in rsync 3.2.3.  This version also began the
    forwarding of a non-default setting to the remote side, though rsync uses
    the backward-compatible options `--msgs2stderr` and `--no-msgs2stderr` to
    represent the `all` and `client` settings, respectively.  A newer rsync
    will continue to accept these older option names to maintain compatibility.

0.  `--quiet`, `-q`

    This option decreases the amount of information you are given during the
    transfer, notably suppressing information messages from the remote server.
    This option is useful when invoking rsync from cron.

0.  `--no-motd`

    This option affects the information that is output by the client at the
    start of a daemon transfer.  This suppresses the message-of-the-day (MOTD)
    text, but it also affects the list of modules that the daemon sends in
    response to the "rsync host::" request (due to a limitation in the rsync
    protocol), so omit this option if you want to request the list of modules
    from the daemon.

0.  `--ignore-times`, `-I`

    Normally rsync will skip any files that are already the same size and have
    the same modification timestamp.  This option turns off this "quick check"
    behavior, causing all files to be updated.

    This option can be confusing compared to [`--ignore-existing`](#opt) and
    [`--ignore-non-existing`](#opt) in that that they cause rsync to transfer
    fewer files, while this option causes rsync to transfer more files.

0.  `--size-only`

    This modifies rsync's "quick check" algorithm for finding files that need
    to be transferred, changing it from the default of transferring files with
    either a changed size or a changed last-modified time to just looking for
    files that have changed in size.  This is useful when starting to use rsync
    after using another mirroring system which may not preserve timestamps
    exactly.

0.  `--modify-window=NUM`, `-@`

    When comparing two timestamps, rsync treats the timestamps as being equal
    if they differ by no more than the modify-window value.  The default is 0,
    which matches just integer seconds.  If you specify a negative value (and
    the receiver is at least version 3.1.3) then nanoseconds will also be taken
    into account.  Specifying 1 is useful for copies to/from MS Windows FAT
    filesystems, because FAT represents times with a 2-second resolution
    (allowing times to differ from the original by up to 1 second).

    If you want all your transfers to default to comparing nanoseconds, you can
    create a `~/.popt` file and put these lines in it:

    >     rsync alias -a -a@-1
    >     rsync alias -t -t@-1

    With that as the default, you'd need to specify `--modify-window=0` (aka
    `-@0`) to override it and ignore nanoseconds, e.g. if you're copying
    between ext3 and ext4, or if the receiving rsync is older than 3.1.3.

0.  `--checksum`, `-c`

    This changes the way rsync checks if the files have been changed and are in
    need of a transfer.  Without this option, rsync uses a "quick check" that
    (by default) checks if each file's size and time of last modification match
    between the sender and receiver.  This option changes this to compare a
    128-bit checksum for each file that has a matching size.  Generating the
    checksums means that both sides will expend a lot of disk I/O reading all
    the data in the files in the transfer, so this can slow things down
    significantly (and this is prior to any reading that will be done to
    transfer changed files)

    The sending side generates its checksums while it is doing the file-system
    scan that builds the list of the available files.  The receiver generates
    its checksums when it is scanning for changed files, and will checksum any
    file that has the same size as the corresponding sender's file: files with
    either a changed size or a changed checksum are selected for transfer.

    Note that rsync always verifies that each _transferred_ file was correctly
    reconstructed on the receiving side by checking a whole-file checksum that
    is generated as the file is transferred, but that automatic
    after-the-transfer verification has nothing to do with this option's
    before-the-transfer "Does this file need to be updated?" check.

    The checksum used is auto-negotiated between the client and the server, but
    can be overridden using either the [`--checksum-choice`](#opt) (`--cc`)
    option or an environment variable that is discussed in that option's
    section.

0.  `--archive`, `-a`

    This is equivalent to `-rlptgoD`.  It is a quick way of saying you want
    recursion and want to preserve almost everything.  Be aware that it does
    **not** include preserving ACLs (`-A`), xattrs (`-X`), atimes (`-U`),
    crtimes (`-N`), nor the finding and preserving of hardlinks (`-H`).

    The only exception to the above equivalence is when [`--files-from`](#opt)
    is specified, in which case [`-r`](#opt) is not implied.

0.  `--no-OPTION`

    You may turn off one or more implied options by prefixing the option name
    with "no-".  Not all positive options have a negated opposite, but a lot
    do, including those that can be used to disable an implied option (e.g.
    `--no-D`, `--no-perms`) or have different defaults in various circumstances
    (e.g. [`--no-whole-file`](#opt), `--no-blocking-io`, `--no-dirs`).  Every
    valid negated option accepts both the short and the long option name after
    the "no-" prefix (e.g. `--no-R` is the same as `--no-relative`).

    As an example, if you want to use [`--archive`](#opt) (`-a`) but don't want
    [`--owner`](#opt) (`-o`), instead of converting `-a` into `-rlptgD`, you
    can specify `-a --no-o` (aka `--archive --no-owner`).

    The order of the options is important: if you specify `--no-r -a`, the `-r`
    option would end up being turned on, the opposite of `-a --no-r`.  Note
    also that the side-effects of the [`--files-from`](#opt) option are NOT
    positional, as it affects the default state of several options and slightly
    changes the meaning of [`-a`](#opt) (see the [`--files-from`](#opt) option
    for more details).

0.  `--recursive`, `-r`

    This tells rsync to copy directories recursively.  See also
    [`--dirs`](#opt) (`-d`) for an option that allows the scanning of a single
    directory.

    See the [`--inc-recursive`](#opt) option for a discussion of the
    incremental recursion for creating the list of files to transfer.

0. `--inc-recursive`, `--i-r`

    This option explicitly enables on incremental recursion when scanning for
    files, which is enabled by default when using the [`--recursive`](#opt)
    option and both sides of the transfer are running rsync 3.0.0 or newer.

    Incremental recursion uses much less memory than non-incremental, while
    also beginning the transfer more quickly (since it doesn't need to scan the
    entire transfer hierarchy before it starts transferring files).  If no
    recursion is enabled in the source files, this option has no effect.

    Some options require rsync to know the full file list, so these options
    disable the incremental recursion mode.  These include:
    - [`--delete-before`](#opt) (the old default of [`--delete`](#opt))
    - [`--delete-after`](#opt)
    - [`--prune-empty-dirs`](#opt)
    - [`--delay-updates`](#opt)

    In order to make [`--delete`](#opt) compatible with incremental recursion,
    rsync 3.0.0 made [`--delete-during`](#opt) the default delete mode (which
    was first added in 2.6.4).

    One side-effect of incremental recursion is that any missing
    sub-directories inside a recursively-scanned directory are (by default)
    created prior to recursing into the sub-dirs.  This earlier creation point
    (compared to a non-incremental recursion) allows rsync to then set the
    modify time of the finished directory right away (without having to delay
    that until a bunch of recursive copying has finished).  However, these
    early directories don't yet have their completed mode, mtime, or ownership
    set -- they have more restrictive rights until the subdirectory's copying
    actually begins.  This early-creation idiom can be avoided by using the
    [`--omit-dir-times`](#opt) option.

    Incremental recursion can be disabled using the
    [`--no-inc-recursive`](#opt) (`--no-i-r`) option.

0. `--no-inc-recursive`, `--no-i-r`

    Disables the new incremental recursion algorithm of the
    [`--recursive`](#opt) option.  This makes rsync scan the full file list
    before it begins to transfer files.  See [`--inc-recursive`](#opt) for more
    info.

0.  `--relative`, `-R`

    Use relative paths.  This means that the full path names specified on the
    command line are sent to the server rather than just the last parts of the
    filenames.  This is particularly useful when you want to send several
    different directories at the same time.  For example, if you used this
    command:

    >     rsync -av /foo/bar/baz.c remote:/tmp/

    would create a file named baz.c in /tmp/ on the remote machine.  If instead
    you used

    >     rsync -avR /foo/bar/baz.c remote:/tmp/

    then a file named /tmp/foo/bar/baz.c would be created on the remote
    machine, preserving its full path.  These extra path elements are called
    "implied directories" (i.e. the "foo" and the "foo/bar" directories in the
    above example).

    Beginning with rsync 3.0.0, rsync always sends these implied directories as
    real directories in the file list, even if a path element is really a
    symlink on the sending side.  This prevents some really unexpected behaviors
    when copying the full path of a file that you didn't realize had a symlink
    in its path.  If you want to duplicate a server-side symlink, include both
    the symlink via its path, and referent directory via its real path.  If
    you're dealing with an older rsync on the sending side, you may need to use
    the [`--no-implied-dirs`](#opt) option.

    It is also possible to limit the amount of path information that is sent as
    implied directories for each path you specify.  With a modern rsync on the
    sending side (beginning with 2.6.7), you can insert a dot and a slash into
    the source path, like this:

    >     rsync -avR /foo/./bar/baz.c remote:/tmp/

    That would create /tmp/bar/baz.c on the remote machine. (Note that the dot
    must be followed by a slash, so "/foo/." would not be abbreviated.) For
    older rsync versions, you would need to use a chdir to limit the source
    path.  For example, when pushing files:

    >     (cd /foo; rsync -avR bar/baz.c remote:/tmp/)

    (Note that the parens put the two commands into a sub-shell, so that the
    "cd" command doesn't remain in effect for future commands.) If you're
    pulling files from an older rsync, use this idiom (but only for a
    non-daemon transfer):

    >     rsync -avR --rsync-path="cd /foo; rsync" \
    >          remote:bar/baz.c /tmp/

0.  `--no-implied-dirs`

    This option affects the default behavior of the [`--relative`](#opt) option.  When
    it is specified, the attributes of the implied directories from the source
    names are not included in the transfer.  This means that the corresponding
    path elements on the destination system are left unchanged if they exist,
    and any missing implied directories are created with default attributes.
    This even allows these implied path elements to have big differences, such
    as being a symlink to a directory on the receiving side.

    For instance, if a command-line arg or a files-from entry told rsync to
    transfer the file "path/foo/file", the directories "path" and "path/foo"
    are implied when [`--relative`](#opt) is used.  If "path/foo" is a symlink to "bar"
    on the destination system, the receiving rsync would ordinarily delete
    "path/foo", recreate it as a directory, and receive the file into the new
    directory.  With `--no-implied-dirs`, the receiving rsync updates
    "path/foo/file" using the existing path elements, which means that the file
    ends up being created in "path/bar".  Another way to accomplish this link
    preservation is to use the [`--keep-dirlinks`](#opt) option (which will also affect
    symlinks to directories in the rest of the transfer).

    When pulling files from an rsync older than 3.0.0, you may need to use this
    option if the sending side has a symlink in the path you request and you
    wish the implied directories to be transferred as normal directories.

0.  `--backup`, `-b`

    With this option, preexisting destination files are renamed as each file is
    transferred or deleted.  You can control where the backup file goes and
    what (if any) suffix gets appended using the [`--backup-dir`](#opt) and
    [`--suffix`](#opt) options.

    If you don't specify [`--backup-dir`](#opt):

    1. the [`--omit-dir-times`](#opt) option will be forced on
    2. the use of [`--delete`](#opt) (without [`--delete-excluded`](#opt)),
       causes rsync to add a "protect" [filter-rule](#FILTER_RULES) for the
       backup suffix to the end of all your existing filters that looks like
       this: `-f "P *~"`.  This rule prevents previously backed-up files from
       being deleted.

    Note that if you are supplying your own filter rules, you may need to
    manually insert your own exclude/protect rule somewhere higher up in the
    list so that it has a high enough priority to be effective (e.g. if your
    rules specify a trailing inclusion/exclusion of `*`, the auto-added rule
    would never be reached).

0.  `--backup-dir=DIR`

    This implies the [`--backup`](#opt) option, and tells rsync to store all
    backups in the specified directory on the receiving side.  This can be used
    for incremental backups.  You can additionally specify a backup suffix
    using the [`--suffix`](#opt) option (otherwise the files backed up in the
    specified directory will keep their original filenames).

    Note that if you specify a relative path, the backup directory will be
    relative to the destination directory, so you probably want to specify
    either an absolute path or a path that starts with "../".  If an rsync
    daemon is the receiver, the backup dir cannot go outside the module's path
    hierarchy, so take extra care not to delete it or copy into it.

0.  `--suffix=SUFFIX`

    This option allows you to override the default backup suffix used with the
    [`--backup`](#opt) (`-b`) option.  The default suffix is a `~` if no
    [`--backup-dir`](#opt) was specified, otherwise it is an empty string.

0.  `--update`, `-u`

    This forces rsync to skip any files which exist on the destination and have
    a modified time that is newer than the source file. (If an existing
    destination file has a modification time equal to the source file's, it
    will be updated if the sizes are different.)

    Note that this does not affect the copying of dirs, symlinks, or other
    special files.  Also, a difference of file format between the sender and
    receiver is always considered to be important enough for an update, no
    matter what date is on the objects.  In other words, if the source has a
    directory where the destination has a file, the transfer would occur
    regardless of the timestamps.

    This option is a [TRANSFER RULE](#TRANSFER_RULES), so don't expect any
    exclude side effects.

    A caution for those that choose to combine [`--inplace`](#opt) with
    `--update`: an interrupted transfer will leave behind a partial file on the
    receiving side that has a very recent modified time, so re-running the
    transfer will probably **not** continue the interrupted file.  As such, it
    is usually best to avoid combining this with[ `--inplace`](#opt) unless you
    have implemented manual steps to handle any interrupted in-progress files.

0.  `--inplace`

    This option changes how rsync transfers a file when its data needs to be
    updated: instead of the default method of creating a new copy of the file
    and moving it into place when it is complete, rsync instead writes the
    updated data directly to the destination file.

    This has several effects:

    - Hard links are not broken.  This means the new data will be visible
      through other hard links to the destination file.  Moreover, attempts to
      copy differing source files onto a multiply-linked destination file will
      result in a "tug of war" with the destination data changing back and
      forth.
    - In-use binaries cannot be updated (either the OS will prevent this from
      happening, or binaries that attempt to swap-in their data will misbehave
      or crash).
    - The file's data will be in an inconsistent state during the transfer and
      will be left that way if the transfer is interrupted or if an update
      fails.
    - A file that rsync cannot write to cannot be updated.  While a super user
      can update any file, a normal user needs to be granted write permission
      for the open of the file for writing to be successful.
    - The efficiency of rsync's delta-transfer algorithm may be reduced if some
      data in the destination file is overwritten before it can be copied to a
      position later in the file.  This does not apply if you use [`--backup`](#opt),
      since rsync is smart enough to use the backup file as the basis file for
      the transfer.

    WARNING: you should not use this option to update files that are being
    accessed by others, so be careful when choosing to use this for a copy.

    This option is useful for transferring large files with block-based changes
    or appended data, and also on systems that are disk bound, not network
    bound.  It can also help keep a copy-on-write filesystem snapshot from
    diverging the entire contents of a file that only has minor changes.

    The option implies [`--partial`](#opt) (since an interrupted transfer does
    not delete the file), but conflicts with [`--partial-dir`](#opt) and
    [`--delay-updates`](#opt).  Prior to rsync 2.6.4 `--inplace` was also
    incompatible with [`--compare-dest`](#opt) and [`--link-dest`](#opt).

0.  `--append`

    This special copy mode only works to efficiently update files that are
    known to be growing larger where any existing content on the receiving side
    is also known to be the same as the content on the sender.  The use of
    `--append` **can be dangerous** if you aren't 100% sure that all the files
    in the transfer are shared, growing files.  You should thus use filter
    rules to ensure that you weed out any files that do not fit this criteria.

    Rsync updates these growing file in-place without verifying any of the
    existing content in the file (it only verifies the content that it is
    appending).  Rsync skips any files that exist on the receiving side that
    are not shorter than the associated file on the sending side (which means
    that new files are transferred).  It also skips any files whose size on the
    sending side gets shorter during the send negotiations (rsync warns about a
    "diminished" file when this happens).

    This does not interfere with the updating of a file's non-content
    attributes (e.g.  permissions, ownership, etc.) when the file does not need
    to be transferred, nor does it affect the updating of any directories or
    non-regular files.

0.  `--append-verify`

    This special copy mode works like [`--append`](#opt) except that all the
    data in the file is included in the checksum verification (making it less
    efficient but also potentially safer).  This option **can be dangerous** if
    you aren't 100% sure that all the files in the transfer are shared, growing
    files.  See the [`--append`](#opt) option for more details.

    Note: prior to rsync 3.0.0, the [`--append`](#opt) option worked like
    `--append-verify`, so if you are interacting with an older rsync (or the
    transfer is using a protocol prior to 30), specifying either append option
    will initiate an `--append-verify` transfer.

0.  `--dirs`, `-d`

    Tell the sending side to include any directories that are encountered.
    Unlike [`--recursive`](#opt), a directory's contents are not copied unless
    the directory name specified is "." or ends with a trailing slash (e.g.
    ".", "dir/.", "dir/", etc.).  Without this option or the
    [`--recursive`](#opt) option, rsync will skip all directories it encounters
    (and output a message to that effect for each one).  If you specify both
    `--dirs` and [`--recursive`](#opt), `--recursive` takes precedence.

    The `--dirs` option is implied by the [`--files-from`](#opt) option or the
    [`--list-only`](#opt) option (including an implied [`--list-only`](#opt)
    usage) if [`--recursive`](#opt) wasn't specified (so that directories are
    seen in the listing).  Specify `--no-dirs` (or `--no-d`) if you want to
    turn this off.

    There is also a backward-compatibility helper option, `--old-dirs`
    (`--old-d`) that tells rsync to use a hack of `-r --exclude='/*/*'` to get
    an older rsync to list a single directory without recursing.

0.  `--mkpath`

    Create all missing path components of the destination path.

    By default, rsync allows only the final component of the destination path
    to not exist, which is an attempt to help you to validate your destination
    path.  With this option, rsync creates all the missing destination-path
    components, just as if `mkdir -p $DEST_PATH` had been run on the receiving
    side.

    When specifying a destination path, including a trailing slash ensures that
    the whole path is treated as directory names to be created, even when the
    file list has a single item. See the [COPYING TO A DIFFERENT NAME](#)
    section for full details on how rsync decides if a final destination-path
    component should be created as a directory or not.

    If you would like the newly-created destination dirs to match the dirs on
    the sending side, you should be using [`--relative`](#opt) (`-R`) instead
    of `--mkpath`.  For instance, the following two commands result in the same
    destination tree, but only the second command ensures that the
    "some/extra/path" components match the dirs on the sending side:

    >     rsync -ai --mkpath host:some/extra/path/*.c some/extra/path/
    >     rsync -aiR host:some/extra/path/*.c ./

0.  `--links`, `-l`

    Add symlinks to the transferred files instead of noisily ignoring them with
    a "non-regular file" warning for each symlink encountered.  You can
    alternately silence the warning by specifying [`--info=nonreg0`](#opt).

    The default handling of symlinks is to recreate each symlink's unchanged
    value on the receiving side.

    See the [SYMBOLIC LINKS](#) section for multi-option info.

0.  `--copy-links`, `-L`

    The sender transforms each symlink encountered in the transfer into the
    referent item, following the symlink chain to the file or directory that it
    references.  If a symlink chain is broken, an error is output and the file
    is dropped from the transfer.

    This option supersedes any other options that affect symlinks in the
    transfer, since there are no symlinks left in the transfer.

    This option does not change the handling of existing symlinks on the
    receiving side, unlike versions of rsync prior to 2.6.3 which had the
    side-effect of telling the receiving side to also follow symlinks.  A
    modern rsync won't forward this option to a remote receiver (since only the
    sender needs to know about it), so this caveat should only affect someone
    using an rsync client older than 2.6.7 (which is when `-L` stopped being
    forwarded to the receiver).

    See the [`--keep-dirlinks`](#opt) (`-K`) if you need a symlink to a
    directory to be treated as a real directory on the receiving side.

    See the [SYMBOLIC LINKS](#) section for multi-option info.

0.  `--copy-unsafe-links`

    This tells rsync to copy the referent of symbolic links that point outside
    the copied tree.  Absolute symlinks are also treated like ordinary files,
    and so are any symlinks in the source path itself when [`--relative`](#opt)
    is used.

    Note that the cut-off point is the top of the transfer, which is the part
    of the path that rsync isn't mentioning in the verbose output.  If you copy
    "/src/subdir" to "/dest/" then the "subdir" directory is a name inside the
    transfer tree, not the top of the transfer (which is /src) so it is legal
    for created relative symlinks to refer to other names inside the /src and
    /dest directories.  If you instead copy "/src/subdir/" (with a trailing
    slash) to "/dest/subdir" that would not allow symlinks to any files outside
    of "subdir".

    Note that safe symlinks are only copied if [`--links`](#opt) was also
    specified or implied. The `--copy-unsafe-links` option has no extra effect
    when combined with [`--copy-links`](#opt).

    See the [SYMBOLIC LINKS](#) section for multi-option info.

0.  `--safe-links`

    This tells the receiving rsync to ignore any symbolic links in the transfer
    which point outside the copied tree.  All absolute symlinks are also
    ignored.

    Since this ignoring is happening on the receiving side, it will still be
    effective even when the sending side has munged symlinks (when it is using
    [`--munge-links`](#opt)). It also affects deletions, since the file being
    present in the transfer prevents any matching file on the receiver from
    being deleted when the symlink is deemed to be unsafe and is skipped.

    This option must be combined with [`--links`](#opt) (or
    [`--archive`](#opt)) to have any symlinks in the transfer to conditionally
    ignore. Its effect is superseded by [`--copy-unsafe-links`](#opt).

    Using this option in conjunction with [`--relative`](#opt) may give
    unexpected results.

    See the [SYMBOLIC LINKS](#) section for multi-option info.

0.  `--munge-links`

    This option affects just one side of the transfer and tells rsync to munge
    symlink values when it is receiving files or unmunge symlink values when it
    is sending files.  The munged values make the symlinks unusable on disk but
    allows the original contents of the symlinks to be recovered.

    The server-side rsync often enables this option without the client's
    knowledge, such as in an rsync daemon's configuration file or by an option
    given to the rrsync (restricted rsync) script.  When specified on the
    client side, specify the option normally if it is the client side that
    has/needs the munged symlinks, or use `-M--munge-links` to give the option
    to the server when it has/needs the munged symlinks.  Note that on a local
    transfer, the client is the sender, so specifying the option directly
    unmunges symlinks while specifying it as a remote option munges symlinks.

    This option has no effect when sent to a daemon via [`--remote-option`](#opt)
    because the daemon configures whether it wants munged symlinks via its
    "`munge symlinks`" parameter.

    The symlink value is munged/unmunged once it is in the transfer, so any
    option that transforms symlinks into non-symlinks occurs prior to the
    munging/unmunging **except** for [`--safe-links`](#opt), which is a choice
    that the receiver makes, so it bases its decision on the munged/unmunged
    value.  This does mean that if a receiver has munging enabled, that using
    [`--safe-links`](#opt) will cause all symlinks to be ignored (since they
    are all absolute).

    The method that rsync uses to munge the symlinks is to prefix each one's
    value with the string "/rsyncd-munged/".  This prevents the links from
    being used as long as the directory does not exist.  When this option is
    enabled, rsync will refuse to run if that path is a directory or a symlink
    to a directory (though it only checks at startup).  See also the
    "munge-symlinks" python script in the support directory of the source code
    for a way to munge/unmunge one or more symlinks in-place.

0.  `--copy-dirlinks`, `-k`

    This option causes the sending side to treat a symlink to a directory as
    though it were a real directory.  This is useful if you don't want symlinks
    to non-directories to be affected, as they would be using
    [`--copy-links`](#opt).

    Without this option, if the sending side has replaced a directory with a
    symlink to a directory, the receiving side will delete anything that is in
    the way of the new symlink, including a directory hierarchy (as long as
    [`--force`](#opt) or [`--delete`](#opt) is in effect).

    See also [`--keep-dirlinks`](#opt) for an analogous option for the
    receiving side.

    `--copy-dirlinks` applies to all symlinks to directories in the source.  If
    you want to follow only a few specified symlinks, a trick you can use is to
    pass them as additional source args with a trailing slash, using
    [`--relative`](#opt) to make the paths match up right.  For example:

    >     rsync -r --relative src/./ src/./follow-me/ dest/

    This works because rsync calls **lstat**(2) on the source arg as given, and
    the trailing slash makes **lstat**(2) follow the symlink, giving rise to a
    directory in the file-list which overrides the symlink found during the
    scan of "src/./".

    See the [SYMBOLIC LINKS](#) section for multi-option info.

0.  `--keep-dirlinks`, `-K`

    This option causes the receiving side to treat a symlink to a directory as
    though it were a real directory, but only if it matches a real directory
    from the sender.  Without this option, the receiver's symlink would be
    deleted and replaced with a real directory.

    For example, suppose you transfer a directory "foo" that contains a file
    "file", but "foo" is a symlink to directory "bar" on the receiver.  Without
    `--keep-dirlinks`, the receiver deletes symlink "foo", recreates it as a
    directory, and receives the file into the new directory.  With
    `--keep-dirlinks`, the receiver keeps the symlink and "file" ends up in
    "bar".

    One note of caution: if you use `--keep-dirlinks`, you must trust all the
    symlinks in the copy or enable the [`--munge-links`](#opt) option on the
    receiving side!  If it is possible for an untrusted user to create their
    own symlink to any real directory, the user could then (on a subsequent
    copy) replace the symlink with a real directory and affect the content of
    whatever directory the symlink references.  For backup copies, you are
    better off using something like a bind mount instead of a symlink to modify
    your receiving hierarchy.

    See also [`--copy-dirlinks`](#opt) for an analogous option for the sending
    side.

    See the [SYMBOLIC LINKS](#) section for multi-option info.

0.  `--hard-links`, `-H`

    This tells rsync to look for hard-linked files in the source and link
    together the corresponding files on the destination.  Without this option,
    hard-linked files in the source are treated as though they were separate
    files.

    This option does NOT necessarily ensure that the pattern of hard links on
    the destination exactly matches that on the source.  Cases in which the
    destination may end up with extra hard links include the following:

    - If the destination contains extraneous hard-links (more linking than what
      is present in the source file list), the copying algorithm will not break
      them explicitly.  However, if one or more of the paths have content
      differences, the normal file-update process will break those extra links
      (unless you are using the [`--inplace`](#opt) option).
    - If you specify a [`--link-dest`](#opt) directory that contains hard
      links, the linking of the destination files against the
      [`--link-dest`](#opt) files can cause some paths in the destination to
      become linked together due to the [`--link-dest`](#opt) associations.

    Note that rsync can only detect hard links between files that are inside
    the transfer set.  If rsync updates a file that has extra hard-link
    connections to files outside the transfer, that linkage will be broken.  If
    you are tempted to use the [`--inplace`](#opt) option to avoid this breakage, be
    very careful that you know how your files are being updated so that you are
    certain that no unintended changes happen due to lingering hard links (and
    see the [`--inplace`](#opt) option for more caveats).

    If incremental recursion is active (see [`--inc-recursive`](#opt)), rsync
    may transfer a missing hard-linked file before it finds that another link
    for that contents exists elsewhere in the hierarchy.  This does not affect
    the accuracy of the transfer (i.e. which files are hard-linked together),
    just its efficiency (i.e. copying the data for a new, early copy of a
    hard-linked file that could have been found later in the transfer in
    another member of the hard-linked set of files).  One way to avoid this
    inefficiency is to disable incremental recursion using the
    [`--no-inc-recursive`](#opt) option.

0.  `--perms`, `-p`

    This option causes the receiving rsync to set the destination permissions
    to be the same as the source permissions. (See also the [`--chmod`](#opt)
    option for a way to modify what rsync considers to be the source
    permissions.)

    When this option is _off_, permissions are set as follows:

    - Existing files (including updated files) retain their existing
      permissions, though the [`--executability`](#opt) option might change
      just the execute permission for the file.
    - New files get their "normal" permission bits set to the source file's
      permissions masked with the receiving directory's default permissions
      (either the receiving process's umask, or the permissions specified via
      the destination directory's default ACL), and their special permission
      bits disabled except in the case where a new directory inherits a setgid
      bit from its parent directory.

    Thus, when `--perms` and [`--executability`](#opt) are both disabled, rsync's
    behavior is the same as that of other file-copy utilities, such as **cp**(1)
    and **tar**(1).

    In summary: to give destination files (both old and new) the source
    permissions, use `--perms`.  To give new files the destination-default
    permissions (while leaving existing files unchanged), make sure that the
    `--perms` option is off and use [`--chmod=ugo=rwX`](#opt) (which ensures
    that all non-masked bits get enabled).  If you'd care to make this latter
    behavior easier to type, you could define a popt alias for it, such as
    putting this line in the file `~/.popt` (the following defines the `-Z`
    option, and includes `--no-g` to use the default group of the destination
    dir):

    >      rsync alias -Z --no-p --no-g --chmod=ugo=rwX

    You could then use this new option in a command such as this one:

    >      rsync -avZ src/ dest/

    (Caveat: make sure that `-a` does not follow `-Z`, or it will re-enable the
    two `--no-*` options mentioned above.)

    The preservation of the destination's setgid bit on newly-created
    directories when `--perms` is off was added in rsync 2.6.7.  Older rsync
    versions erroneously preserved the three special permission bits for
    newly-created files when `--perms` was off, while overriding the
    destination's setgid bit setting on a newly-created directory.  Default ACL
    observance was added to the ACL patch for rsync 2.6.7, so older (or
    non-ACL-enabled) rsyncs use the umask even if default ACLs are present.
    (Keep in mind that it is the version of the receiving rsync that affects
    these behaviors.)

0.  `--executability`, `-E`

    This option causes rsync to preserve the executability (or
    non-executability) of regular files when [`--perms`](#opt) is not enabled.
    A regular file is considered to be executable if at least one 'x' is turned
    on in its permissions.  When an existing destination file's executability
    differs from that of the corresponding source file, rsync modifies the
    destination file's permissions as follows:

    - To make a file non-executable, rsync turns off all its 'x' permissions.
    - To make a file executable, rsync turns on each 'x' permission that has a
      corresponding 'r' permission enabled.

    If [`--perms`](#opt) is enabled, this option is ignored.

0.  `--acls`, `-A`

    This option causes rsync to update the destination ACLs to be the same as
    the source ACLs.  The option also implies [`--perms`](#opt).

    The source and destination systems must have compatible ACL entries for
    this option to work properly.  See the [`--fake-super`](#opt) option for a
    way to backup and restore ACLs that are not compatible.

0.  `--xattrs`, `-X`

    This option causes rsync to update the destination extended attributes to
    be the same as the source ones.

    For systems that support extended-attribute namespaces, a copy being done
    by a super-user copies all namespaces except system.\*.  A normal user only
    copies the user.\* namespace.  To be able to backup and restore non-user
    namespaces as a normal user, see the [`--fake-super`](#opt) option.

    The above name filtering can be overridden by using one or more filter
    options with the **x** modifier.  When you specify an xattr-affecting
    filter rule, rsync requires that you do your own system/user filtering, as
    well as any additional filtering for what xattr names are copied and what
    names are allowed to be deleted.  For example, to skip the system
    namespace, you could specify:

    >     --filter='-x system.*'

    To skip all namespaces except the user namespace, you could specify a
    negated-user match:

    >     --filter='-x! user.*'

    To prevent any attributes from being deleted, you could specify a
    receiver-only rule that excludes all names:

    >     --filter='-xr *'

    Note that the `-X` option does not copy rsync's special xattr values (e.g.
    those used by [`--fake-super`](#opt)) unless you repeat the option (e.g. `-XX`).
    This "copy all xattrs" mode cannot be used with [`--fake-super`](#opt).

0.  `--chmod=CHMOD`

    This option tells rsync to apply one or more comma-separated "chmod" modes
    to the permission of the files in the transfer.  The resulting value is
    treated as though it were the permissions that the sending side supplied
    for the file, which means that this option can seem to have no effect on
    existing files if [`--perms`](#opt) is not enabled.

    In addition to the normal parsing rules specified in the **chmod**(1)
    manpage, you can specify an item that should only apply to a directory by
    prefixing it with a 'D', or specify an item that should only apply to a
    file by prefixing it with a 'F'.  For example, the following will ensure
    that all directories get marked set-gid, that no files are other-writable,
    that both are user-writable and group-writable, and that both have
    consistent executability across all bits:

    >     --chmod=Dg+s,ug+w,Fo-w,+X

    Using octal mode numbers is also allowed:

    >     --chmod=D2775,F664

    It is also legal to specify multiple `--chmod` options, as each additional
    option is just appended to the list of changes to make.

    See the [`--perms`](#opt) and [`--executability`](#opt) options for how the
    resulting permission value can be applied to the files in the transfer.

0.  `--owner`, `-o`

    This option causes rsync to set the owner of the destination file to be the
    same as the source file, but only if the receiving rsync is being run as
    the super-user (see also the [`--super`](#opt) and [`--fake-super`](#opt)
    options).  Without this option, the owner of new and/or transferred files
    are set to the invoking user on the receiving side.

    The preservation of ownership will associate matching names by default, but
    may fall back to using the ID number in some circumstances (see also the
    [`--numeric-ids`](#opt) option for a full discussion).

0.  `--group`, `-g`

    This option causes rsync to set the group of the destination file to be the
    same as the source file.  If the receiving program is not running as the
    super-user (or if `--no-super` was specified), only groups that the
    invoking user on the receiving side is a member of will be preserved.
    Without this option, the group is set to the default group of the invoking
    user on the receiving side.

    The preservation of group information will associate matching names by
    default, but may fall back to using the ID number in some circumstances
    (see also the [`--numeric-ids`](#opt) option for a full discussion).

0.  `--devices`

    This option causes rsync to transfer character and block device files to
    the remote system to recreate these devices.  If the receiving rsync is not
    being run as the super-user, rsync silently skips creating the device files
    (see also the [`--super`](#opt) and [`--fake-super`](#opt) options).

    By default, rsync generates a "non-regular file" warning for each device
    file encountered when this option is not set.  You can silence the warning
    by specifying [`--info=nonreg0`](#opt).

0.  `--specials`

    This option causes rsync to transfer special files, such as named sockets
    and fifos.  If the receiving rsync is not being run as the super-user,
    rsync silently skips creating the special files (see also the
    [`--super`](#opt) and [`--fake-super`](#opt) options).

    By default, rsync generates a "non-regular file" warning for each special
    file encountered when this option is not set.  You can silence the warning
    by specifying [`--info=nonreg0`](#opt).

0.  `-D`

    The `-D` option is equivalent to "[`--devices`](#opt)
    [`--specials`](#opt)".

0.  `--copy-devices`

    This tells rsync to treat a device on the sending side as a regular file,
    allowing it to be copied to a normal destination file (or another device
    if `--write-devices` was also specified).

    This option is refused by default by an rsync daemon.

0.  `--write-devices`

    This tells rsync to treat a device on the receiving side as a regular file,
    allowing the writing of file data into a device.

    This option implies the [`--inplace`](#opt) option.

    Be careful using this, as you should know what devices are present on the
    receiving side of the transfer, especially when running rsync as root.

    This option is refused by default by an rsync daemon.

0.  `--times`, `-t`

    This tells rsync to transfer modification times along with the files and
    update them on the remote system.  Note that if this option is not used,
    the optimization that excludes files that have not been modified cannot be
    effective; in other words, a missing `-t` (or [`-a`](#opt)) will cause the
    next transfer to behave as if it used [`--ignore-times`](#opt) (`-I`),
    causing all files to be updated (though rsync's delta-transfer algorithm
    will make the update fairly efficient if the files haven't actually
    changed, you're much better off using `-t`).

    A modern rsync that is using transfer protocol 30 or 31 conveys a modify
    time using up to 8-bytes. If rsync is forced to speak an older protocol
    (perhaps due to the remote rsync being older than 3.0.0) a modify time is
    conveyed using 4-bytes. Prior to 3.2.7, these shorter values could convey
    a date range of 13-Dec-1901 to 19-Jan-2038.  Beginning with 3.2.7, these
    4-byte values now convey a date range of 1-Jan-1970 to 7-Feb-2106.  If you
    have files dated older than 1970, make sure your rsync executables are
    upgraded so that the full range of dates can be conveyed.

0.  `--atimes`, `-U`

    This tells rsync to set the access (use) times of the destination files to
    the same value as the source files.

    If repeated, it also sets the [`--open-noatime`](#opt) option, which can help you
    to make the sending and receiving systems have the same access times on the
    transferred files without needing to run rsync an extra time after a file
    is transferred.

    Note that some older rsync versions (prior to 3.2.0) may have been built
    with a pre-release `--atimes` patch that does not imply
    [`--open-noatime`](#opt) when this option is repeated.

0.  `--open-noatime`

    This tells rsync to open files with the O_NOATIME flag (on systems that
    support it) to avoid changing the access time of the files that are being
    transferred.  If your OS does not support the O_NOATIME flag then rsync
    will silently ignore this option.  Note also that some filesystems are
    mounted to avoid updating the atime on read access even without the
    O_NOATIME flag being set.

0.  `--crtimes`, `-N,`

    This tells rsync to set the create times (newness) of the destination
    files to the same value as the source files.

0.  `--omit-dir-times`, `-O`

    This tells rsync to omit directories when it is preserving modification,
    access, and create times.  If NFS is sharing the directories on the receiving
    side, it is a good idea to use `-O`.  This option is inferred if you use
    [`--backup`](#opt) without [`--backup-dir`](#opt).

    This option also has the side-effect of avoiding early creation of missing
    sub-directories when incremental recursion is enabled, as discussed in the
    [`--inc-recursive`](#opt) section.

0.  `--omit-link-times`, `-J`

    This tells rsync to omit symlinks when it is preserving modification,
    access, and create times.

0.  `--super`

    This tells the receiving side to attempt super-user activities even if the
    receiving rsync wasn't run by the super-user.  These activities include:
    preserving users via the [`--owner`](#opt) option, preserving all groups
    (not just the current user's groups) via the [`--group`](#opt) option, and
    copying devices via the [`--devices`](#opt) option.  This is useful for
    systems that allow such activities without being the super-user, and also
    for ensuring that you will get errors if the receiving side isn't being run
    as the super-user.  To turn off super-user activities, the super-user can
    use `--no-super`.

0.  `--fake-super`

    When this option is enabled, rsync simulates super-user activities by
    saving/restoring the privileged attributes via special extended attributes
    that are attached to each file (as needed).  This includes the file's owner
    and group (if it is not the default), the file's device info (device &
    special files are created as empty text files), and any permission bits
    that we won't allow to be set on the real file (e.g. the real file gets
    u-s,g-s,o-t for safety) or that would limit the owner's access (since the
    real super-user can always access/change a file, the files we create can
    always be accessed/changed by the creating user).  This option also handles
    ACLs (if [`--acls`](#opt) was specified) and non-user extended attributes
    (if [`--xattrs`](#opt) was specified).

    This is a good way to backup data without using a super-user, and to store
    ACLs from incompatible systems.

    The `--fake-super` option only affects the side where the option is used.
    To affect the remote side of a remote-shell connection, use the
    [`--remote-option`](#opt) (`-M`) option:

    >     rsync -av -M--fake-super /src/ host:/dest/

    For a local copy, this option affects both the source and the destination.
    If you wish a local copy to enable this option just for the destination
    files, specify `-M--fake-super`.  If you wish a local copy to enable this
    option just for the source files, combine `--fake-super` with `-M--super`.

    This option is overridden by both [`--super`](#opt) and `--no-super`.

    See also the [`fake super`](rsyncd.conf.5#fake_super) setting in the
    daemon's rsyncd.conf file.

0.  `--sparse`, `-S`

    Try to handle sparse files efficiently so they take up less space on the
    destination.  If combined with [`--inplace`](#opt) the file created might
    not end up with sparse blocks with some combinations of kernel version
    and/or filesystem type.  If [`--whole-file`](#opt) is in effect (e.g. for a
    local copy) then it will always work because rsync truncates the file prior
    to writing out the updated version.

    Note that versions of rsync older than 3.1.3 will reject the combination of
    `--sparse` and [`--inplace`](#opt).

0.  `--preallocate`

    This tells the receiver to allocate each destination file to its eventual
    size before writing data to the file.  Rsync will only use the real
    filesystem-level preallocation support provided by Linux's **fallocate**(2)
    system call or Cygwin's **posix_fallocate**(3), not the slow glibc
    implementation that writes a null byte into each block.

    Without this option, larger files may not be entirely contiguous on the
    filesystem, but with this option rsync will probably copy more slowly.  If
    the destination is not an extent-supporting filesystem (such as ext4, xfs,
    NTFS, etc.), this option may have no positive effect at all.

    If combined with [`--sparse`](#opt), the file will only have sparse blocks
    (as opposed to allocated sequences of null bytes) if the kernel version and
    filesystem type support creating holes in the allocated data.

0.  `--dry-run`, `-n`

    This makes rsync perform a trial run that doesn't make any changes (and
    produces mostly the same output as a real run).  It is most commonly used
    in combination with the [`--verbose`](#opt) (`-v`) and/or
    [`--itemize-changes`](#opt) (`-i`) options to see what an rsync command is
    going to do before one actually runs it.

    The output of [`--itemize-changes`](#opt) is supposed to be exactly the
    same on a dry run and a subsequent real run (barring intentional trickery
    and system call failures); if it isn't, that's a bug.  Other output should
    be mostly unchanged, but may differ in some areas.  Notably, a dry run does
    not send the actual data for file transfers, so [`--progress`](#opt) has no
    effect, the "bytes sent", "bytes received", "literal data", and "matched
    data" statistics are too small, and the "speedup" value is equivalent to a
    run where no file transfers were needed.

0.  `--whole-file`, `-W`

    This option disables rsync's delta-transfer algorithm, which causes all
    transferred files to be sent whole.  The transfer may be faster if this
    option is used when the bandwidth between the source and destination
    machines is higher than the bandwidth to disk (especially when the "disk"
    is actually a networked filesystem).  This is the default when both the
    source and destination are specified as local paths, but only if no
    batch-writing option is in effect.

0. `--no-whole-file`, `--no-W`

    Disable whole-file updating when it is enabled by default for a local
    transfer.  This usually slows rsync down, but it can be useful if you are
    trying to minimize the writes to the destination file (if combined with
    [`--inplace`](#opt)) or for testing the checksum-based update algorithm.

    See also the [`--whole-file`](#opt) option.

0.  `--checksum-choice=STR`, `--cc=STR`

    This option overrides the checksum algorithms.  If one algorithm name is
    specified, it is used for both the transfer checksums and (assuming
    [`--checksum`](#opt) is specified) the pre-transfer checksums.  If two
    comma-separated names are supplied, the first name affects the transfer
    checksums, and the second name affects the pre-transfer checksums (`-c`).

    The checksum options that you may be able to use are:

    - `auto` (the default automatic choice)
    - `xxh128`
    - `xxh3`
    - `xxh64` (aka `xxhash`)
    - `md5`
    - `md4`
    - `sha1`
    - `none`

    Run `rsync --version` to see the default checksum list compiled into your
    version (which may differ from the list above).

    If "none" is specified for the first (or only) name, the [`--whole-file`](#opt)
    option is forced on and no checksum verification is performed on the
    transferred data.  If "none" is specified for the second (or only) name,
    the [`--checksum`](#opt) option cannot be used.

    The "auto" option is the default, where rsync bases its algorithm choice on
    a negotiation between the client and the server as follows:

    When both sides of the transfer are at least 3.2.0, rsync chooses the first
    algorithm in the client's list of choices that is also in the server's list
    of choices.  If no common checksum choice is found, rsync exits with
    an error.  If the remote rsync is too old to support checksum negotiation,
    a value is chosen based on the protocol version (which chooses between MD5
    and various flavors of MD4 based on protocol age).

    The default order can be customized by setting the environment variable
    [`RSYNC_CHECKSUM_LIST`](#) to a space-separated list of acceptable checksum
    names.  If the string contains a "`&`" character, it is separated into the
    "client string & server string", otherwise the same string applies to both.
    If the string (or string portion) contains no non-whitespace characters,
    the default checksum list is used.  This method does not allow you to
    specify the transfer checksum separately from the pre-transfer checksum,
    and it discards "auto" and all unknown checksum names.  A list with only
    invalid names results in a failed negotiation.

    The use of the `--checksum-choice` option overrides this environment list.

0.  `--one-file-system`, `-x`

    This tells rsync to avoid crossing a filesystem boundary when recursing.
    This does not limit the user's ability to specify items to copy from
    multiple filesystems, just rsync's recursion through the hierarchy of each
    directory that the user specified, and also the analogous recursion on the
    receiving side during deletion.  Also keep in mind that rsync treats a
    "bind" mount to the same device as being on the same filesystem.

    If this option is repeated, rsync omits all mount-point directories from
    the copy.  Otherwise, it includes an empty directory at each mount-point it
    encounters (using the attributes of the mounted directory because those of
    the underlying mount-point directory are inaccessible).

    If rsync has been told to collapse symlinks (via [`--copy-links`](#opt) or
    [`--copy-unsafe-links`](#opt)), a symlink to a directory on another device
    is treated like a mount-point.  Symlinks to non-directories are unaffected
    by this option.

0.  `--ignore-non-existing`, `--existing`

    This tells rsync to skip creating files (including directories) that do not
    exist yet on the destination.  If this option is combined with the
    [`--ignore-existing`](#opt) option, no files will be updated (which can be
    useful if all you want to do is delete extraneous files).

    This option is a [TRANSFER RULE](#TRANSFER_RULES), so don't expect any
    exclude side effects.

0.  `--ignore-existing`

    This tells rsync to skip updating files that already exist on the
    destination (this does _not_ ignore existing directories, or nothing would
    get done).  See also [`--ignore-non-existing`](#opt).

    This option is a [TRANSFER RULE](#TRANSFER_RULES), so don't expect any
    exclude side effects.

    This option can be useful for those doing backups using the
    [`--link-dest`](#opt) option when they need to continue a backup run that
    got interrupted.  Since a [`--link-dest`](#opt) run is copied into a new
    directory hierarchy (when it is used properly), using [`--ignore-existing`
    will ensure that the already-handled files don't get tweaked (which avoids
    a change in permissions on the hard-linked files).  This does mean that
    this option is only looking at the existing files in the destination
    hierarchy itself.

    When [`--info=skip2`](#opt) is used rsync will output "FILENAME exists
    (INFO)" messages where the INFO indicates one of "type change", "sum
    change" (requires [`-c`](#opt)), "file change" (based on the quick check),
    "attr change", or "uptodate".  Using [`--info=skip1`](#opt) (which is also
    implied by 2 [`-v`](#opt) options) outputs the exists message without the
    INFO suffix.

0.  `--remove-source-files`

    This tells rsync to remove from the sending side the files (meaning
    non-directories) that are a part of the transfer and have been successfully
    duplicated on the receiving side.

    Note that you should only use this option on source files that are
    quiescent.  If you are using this to move files that show up in a
    particular directory over to another host, make sure that the finished
    files get renamed into the source directory, not directly written into it,
    so that rsync can't possibly transfer a file that is not yet fully written.
    If you can't first write the files into a different directory, you should
    use a naming idiom that lets rsync avoid transferring files that are not
    yet finished (e.g. name the file "foo.new" when it is written, rename it to
    "foo" when it is done, and then use the option [`--exclude='*.new'`](#opt)
    for the rsync transfer).

    Starting with 3.1.0, rsync will skip the sender-side removal (and output an
    error) if the file's size or modify time has not stayed unchanged.

    Starting with 3.2.6, a local rsync copy will ensure that the sender does
    not remove a file the receiver just verified, such as when the user
    accidentally makes the source and destination directory the same path.

0.  `--delete`

    This tells rsync to delete extraneous files from the receiving side (ones
    that aren't on the sending side), but only for the directories that are
    being synchronized.  You must have asked rsync to send the whole directory
    (e.g. "`dir`" or "`dir/`") without using a wildcard for the directory's
    contents (e.g. "`dir/*`") since the wildcard is expanded by the shell and
    rsync thus gets a request to transfer individual files, not the files'
    parent directory.  Files that are excluded from the transfer are also
    excluded from being deleted unless you use the [`--delete-excluded`](#opt)
    option or mark the rules as only matching on the sending side (see the
    include/exclude modifiers in the [FILTER RULES](#) section).

    Prior to rsync 2.6.7, this option would have no effect unless
    [`--recursive`](#opt) was enabled.  Beginning with 2.6.7, deletions will
    also occur when [`--dirs`](#opt) (`-d`) is enabled, but only for
    directories whose contents are being copied.

    This option can be dangerous if used incorrectly! It is a very good idea to
    first try a run using the [`--dry-run`](#opt) (`-n`) option to see what
    files are going to be deleted.

    If the sending side detects any I/O errors, then the deletion of any files
    at the destination will be automatically disabled.  This is to prevent
    temporary filesystem failures (such as NFS errors) on the sending side from
    causing a massive deletion of files on the destination.  You can override
    this with the [`--ignore-errors`](#opt) option.

    The `--delete` option may be combined with one of the --delete-WHEN options
    without conflict, as well as [`--delete-excluded`](#opt).  However, if none
    of the `--delete-WHEN` options are specified, rsync will choose the
    [`--delete-during`](#opt) algorithm when talking to rsync 3.0.0 or newer,
    or the [`--delete-before`](#opt) algorithm when talking to an older rsync.
    See also [`--delete-delay`](#opt) and [`--delete-after`](#opt).

0.  `--delete-before`

    Request that the file-deletions on the receiving side be done before the
    transfer starts.  See [`--delete`](#opt) (which is implied) for more
    details on file-deletion.

    Deleting before the transfer is helpful if the filesystem is tight for
    space and removing extraneous files would help to make the transfer
    possible.  However, it does introduce a delay before the start of the
    transfer, and this delay might cause the transfer to timeout (if
    [`--timeout`](#opt) was specified).  It also forces rsync to use the old,
    non-incremental recursion algorithm that requires rsync to scan all the
    files in the transfer into memory at once (see [`--recursive`](#opt)).

0.  `--delete-during`, `--del`

    Request that the file-deletions on the receiving side be done incrementally
    as the transfer happens.  The per-directory delete scan is done right
    before each directory is checked for updates, so it behaves like a more
    efficient [`--delete-before`](#opt), including doing the deletions prior to
    any per-directory filter files being updated.  This option was first added
    in rsync version 2.6.4.  See [`--delete`](#opt) (which is implied) for more
    details on file-deletion.

0.  `--delete-delay`

    Request that the file-deletions on the receiving side be computed during
    the transfer (like [`--delete-during`](#opt)), and then removed after the
    transfer completes.  This is useful when combined with
    [`--delay-updates`](#opt) and/or [`--fuzzy`](#opt), and is more efficient
    than using [`--delete-after`](#opt) (but can behave differently, since
    [`--delete-after`](#opt) computes the deletions in a separate pass after
    all updates are done).  If the number of removed files overflows an
    internal buffer, a temporary file will be created on the receiving side to
    hold the names (it is removed while open, so you shouldn't see it during
    the transfer).  If the creation of the temporary file fails, rsync will try
    to fall back to using [`--delete-after`](#opt) (which it cannot do if
    [`--recursive`](#opt) is doing an incremental scan).  See
    [`--delete`](#opt) (which is implied) for more details on file-deletion.

0.  `--delete-after`

    Request that the file-deletions on the receiving side be done after the
    transfer has completed.  This is useful if you are sending new
    per-directory merge files as a part of the transfer and you want their
    exclusions to take effect for the delete phase of the current transfer.  It
    also forces rsync to use the old, non-incremental recursion algorithm that
    requires rsync to scan all the files in the transfer into memory at once
    (see [`--recursive`](#opt)). See [`--delete`](#opt) (which is implied) for
    more details on file-deletion.

    See also the [`--delete-delay`](#opt) option that might be a faster choice
    for those that just want the deletions to occur at the end of the transfer.

0.  `--delete-excluded`

    This option turns any unqualified exclude/include rules into server-side
    rules that do not affect the receiver's deletions.

    By default, an exclude or include has both a server-side effect (to "hide"
    and "show" files when building the server's file list) and a receiver-side
    effect (to "protect" and "risk" files when deletions are occurring).  Any
    rule that has no modifier to specify what sides it is executed on will be
    instead treated as if it were a server-side rule only, avoiding any
    "protect" effects of the rules.

    A rule can still apply to both sides even with this option specified if the
    rule is given both the sender & receiver modifier letters (e.g., `-f'-sr
    foo'`).  Receiver-side protect/risk rules can also be explicitly specified
    to limit the deletions.  This saves you from having to edit a bunch of
    `-f'- foo'` rules into `-f'-s foo'` (aka `-f'H foo'`) rules (not to mention
    the corresponding includes).

    See the [FILTER RULES](#) section for more information.  See
    [`--delete`](#opt) (which is implied) for more details on deletion.

0.  `--ignore-missing-args`

    When rsync is first processing the explicitly requested source files (e.g.
    command-line arguments or [`--files-from`](#opt) entries), it is normally
    an error if the file cannot be found.  This option suppresses that error,
    and does not try to transfer the file.  This does not affect subsequent
    vanished-file errors if a file was initially found to be present and later
    is no longer there.

0.  `--delete-missing-args`

    This option takes the behavior of the (implied)
    [`--ignore-missing-args`](#opt) option a step farther: each missing arg
    will become a deletion request of the corresponding destination file on the
    receiving side (should it exist).  If the destination file is a non-empty
    directory, it will only be successfully deleted if [`--force`](#opt) or
    [`--delete`](#opt) are in effect.  Other than that, this option is
    independent of any other type of delete processing.

    The missing source files are represented by special file-list entries which
    display as a "`*missing`" entry in the [`--list-only`](#opt) output.

0.  `--ignore-errors`

    Tells [`--delete`](#opt) to go ahead and delete files even when there are
    I/O errors.

0.  `--force`

    This option tells rsync to delete a non-empty directory when it is to be
    replaced by a non-directory.  This is only relevant if deletions are not
    active (see [`--delete`](#opt) for details).

    Note for older rsync versions: `--force` used to still be required when
    using [`--delete-after`](#opt), and it used to be non-functional unless the
    [`--recursive`](#opt) option was also enabled.

0.  `--max-delete=NUM`

    This tells rsync not to delete more than NUM files or directories.  If that
    limit is exceeded, all further deletions are skipped through the end of the
    transfer.  At the end, rsync outputs a warning (including a count of the
    skipped deletions) and exits with an error code of 25 (unless some more
    important error condition also occurred).

    Beginning with version 3.0.0, you may specify `--max-delete=0` to be warned
    about any extraneous files in the destination without removing any of them.
    Older clients interpreted this as "unlimited", so if you don't know what
    version the client is, you can use the less obvious `--max-delete=-1` as a
    backward-compatible way to specify that no deletions be allowed (though
    really old versions didn't warn when the limit was exceeded).

0.  `--max-size=SIZE`

    This tells rsync to avoid transferring any file that is larger than the
    specified SIZE.  A numeric value can be suffixed with a string to indicate
    the numeric units or left unqualified to specify bytes.  Feel free to use a
    fractional value along with the units, such as `--max-size=1.5m`.

    This option is a [TRANSFER RULE](#TRANSFER_RULES), so don't expect any
    exclude side effects.

    The first letter of a units string can be `B` (bytes), `K` (kilo), `M`
    (mega), `G` (giga), `T` (tera), or `P` (peta).  If the string is a single
    char or has "ib" added to it (e.g. "G" or "GiB") then the units are
    multiples of 1024.  If you use a two-letter suffix that ends with a "B"
    (e.g. "kb") then you get units that are multiples of 1000.  The string's
    letters can be any mix of upper and lower-case that you want to use.

    Finally, if the string ends with either "+1" or "-1", it is offset by one
    byte in the indicated direction.  The largest possible value is usually
    `8192P-1`.

    Examples: `--max-size=1.5mb-1` is 1499999 bytes, and `--max-size=2g+1` is
    2147483649 bytes.

    Note that rsync versions prior to 3.1.0 did not allow `--max-size=0`.

0.  `--min-size=SIZE`

    This tells rsync to avoid transferring any file that is smaller than the
    specified SIZE, which can help in not transferring small, junk files.  See
    the [`--max-size`](#opt) option for a description of SIZE and other info.

    Note that rsync versions prior to 3.1.0 did not allow `--min-size=0`.

0.  `--max-alloc=SIZE`

    By default rsync limits an individual malloc/realloc to about 1GB in size.
    For most people this limit works just fine and prevents a protocol error
    causing rsync to request massive amounts of memory.  However, if you have
    many millions of files in a transfer, a large amount of server memory, and
    you don't want to split up your transfer into multiple parts, you can
    increase the per-allocation limit to something larger and rsync will
    consume more memory.

    Keep in mind that this is not a limit on the total size of allocated
    memory.  It is a sanity-check value for each individual allocation.

    See the [`--max-size`](#opt) option for a description of how SIZE can be
    specified.  The default suffix if none is given is bytes.

    Beginning in 3.2.3, a value of 0 specifies no limit.

    You can set a default value using the environment variable
    [`RSYNC_MAX_ALLOC`](#) using the same SIZE values as supported by this
    option.  If the remote rsync doesn't understand the `--max-alloc` option,
    you can override an environmental value by specifying `--max-alloc=1g`,
    which will make rsync avoid sending the option to the remote side (because
    "1G" is the default).

0.  `--block-size=SIZE`, `-B`

    This forces the block size used in rsync's delta-transfer algorithm to a
    fixed value.  It is normally selected based on the size of each file being
    updated.  See the technical report for details.

    Beginning in 3.2.3 the SIZE can be specified with a suffix as detailed in
    the [`--max-size`](#opt) option.  Older versions only accepted a byte count.

0.  `--rsh=COMMAND`, `-e`

    This option allows you to choose an alternative remote shell program to use
    for communication between the local and remote copies of rsync.  Typically,
    rsync is configured to use ssh by default, but you may prefer to use rsh on
    a local network.

    If this option is used with `[user@]host::module/path`, then the remote
    shell _COMMAND_ will be used to run an rsync daemon on the remote host, and
    all data will be transmitted through that remote shell connection, rather
    than through a direct socket connection to a running rsync daemon on the
    remote host.  See the [USING RSYNC-DAEMON FEATURES VIA A REMOTE-SHELL
    CONNECTION](#) section above.

    Beginning with rsync 3.2.0, the [`RSYNC_PORT`](#) environment variable will
    be set when a daemon connection is being made via a remote-shell
    connection.  It is set to 0 if the default daemon port is being assumed, or
    it is set to the value of the rsync port that was specified via either the
    [`--port`](#opt) option or a non-empty port value in an `rsync://` URL.
    This allows the script to discern if a non-default port is being requested,
    allowing for things such as an SSL or stunnel helper script to connect to a
    default or alternate port.

    Command-line arguments are permitted in COMMAND provided that COMMAND is
    presented to rsync as a single argument.  You must use spaces (not tabs or
    other whitespace) to separate the command and args from each other, and you
    can use single- and/or double-quotes to preserve spaces in an argument (but
    not backslashes).  Note that doubling a single-quote inside a single-quoted
    string gives you a single-quote; likewise for double-quotes (though you
    need to pay attention to which quotes your shell is parsing and which
    quotes rsync is parsing).  Some examples:

    >     -e 'ssh -p 2234'
    >     -e 'ssh -o "ProxyCommand nohup ssh firewall nc -w1 %h %p"'

    (Note that ssh users can alternately customize site-specific connect
    options in their .ssh/config file.)

    You can also choose the remote shell program using the [`RSYNC_RSH`](#)
    environment variable, which accepts the same range of values as `-e`.

    See also the [`--blocking-io`](#opt) option which is affected by this
    option.

0.  `--rsync-path=PROGRAM`

    Use this to specify what program is to be run on the remote machine to
    start-up rsync.  Often used when rsync is not in the default remote-shell's
    path (e.g. `--rsync-path=/usr/local/bin/rsync`).  Note that PROGRAM is run
    with the help of a shell, so it can be any program, script, or command
    sequence you'd care to run, so long as it does not corrupt the standard-in
    & standard-out that rsync is using to communicate.

    One tricky example is to set a different default directory on the remote
    machine for use with the [`--relative`](#opt) option.  For instance:

    >     rsync -avR --rsync-path="cd /a/b && rsync" host:c/d /e/

0.  `--remote-option=OPTION`, `-M`

    This option is used for more advanced situations where you want certain
    effects to be limited to one side of the transfer only.  For instance, if
    you want to pass [`--log-file=FILE`](#opt) and [`--fake-super`](#opt) to
    the remote system, specify it like this:

    >     rsync -av -M --log-file=foo -M--fake-super src/ dest/

    If you want to have an option affect only the local side of a transfer when
    it normally affects both sides, send its negation to the remote side.  Like
    this:

    >     rsync -av -x -M--no-x src/ dest/

    Be cautious using this, as it is possible to toggle an option that will
    cause rsync to have a different idea about what data to expect next over
    the socket, and that will make it fail in a cryptic fashion.

    Note that you should use a separate `-M` option for each remote option you
    want to pass.  On older rsync versions, the presence of any spaces in the
    remote-option arg could cause it to be split into separate remote args, but
    this requires the use of [`--old-args`](#opt) in a modern rsync.

    When performing a local transfer, the "local" side is the sender and the
    "remote" side is the receiver.

    Note some versions of the popt option-parsing library have a bug in them
    that prevents you from using an adjacent arg with an equal in it next to a
    short option letter (e.g. `-M--log-file=/tmp/foo`).  If this bug affects
    your version of popt, you can use the version of popt that is included with
    rsync.

0.  `--cvs-exclude`, `-C`

    This is a useful shorthand for excluding a broad range of files that you
    often don't want to transfer between systems.  It uses a similar algorithm
    to CVS to determine if a file should be ignored.

    The exclude list is initialized to exclude the following items (these
    initial items are marked as perishable -- see the [FILTER RULES](#)
    section):

    [comment]: # (This list gets used for the default-cvsignore.h file.)

    > `RCS`
    > `SCCS`
    > `CVS`
    > `CVS.adm`
    > `RCSLOG`
    > `cvslog.*`
    > `tags`
    > `TAGS`
    > `.make.state`
    > `.nse_depinfo`
    > `*~`
    > `#*`
    > `.#*`
    > `,*`
    > `_$*`
    > `*$`
    > `*.old`
    > `*.bak`
    > `*.BAK`
    > `*.orig`
    > `*.rej`
    > `.del-*`
    > `*.a`
    > `*.olb`
    > `*.o`
    > `*.obj`
    > `*.so`
    > `*.exe`
    > `*.Z`
    > `*.elc`
    > `*.ln`
    > `core`
    > `.svn/`
    > `.git/`
    > `.hg/`
    > `.bzr/`

    then, files listed in a $HOME/.cvsignore are added to the list and any
    files listed in the CVSIGNORE environment variable (all cvsignore names are
    delimited by whitespace).

    Finally, any file is ignored if it is in the same directory as a .cvsignore
    file and matches one of the patterns listed therein.  Unlike rsync's
    filter/exclude files, these patterns are split on whitespace.  See the
    **cvs**(1) manual for more information.

    If you're combining `-C` with your own [`--filter`](#opt) rules, you should
    note that these CVS excludes are appended at the end of your own rules,
    regardless of where the `-C` was placed on the command-line.  This makes
    them a lower priority than any rules you specified explicitly.  If you want
    to control where these CVS excludes get inserted into your filter rules,
    you should omit the `-C` as a command-line option and use a combination of
    [`--filter=:C`](#opt) and [`--filter=-C`](#opt) (either on your
    command-line or by putting the ":C" and "-C" rules into a filter file with
    your other rules).  The first option turns on the per-directory scanning
    for the .cvsignore file.  The second option does a one-time import of the
    CVS excludes mentioned above.

0.  `--filter=RULE`, `-f`

    This option allows you to add rules to selectively exclude certain files
    from the list of files to be transferred.  This is most useful in
    combination with a recursive transfer.

    You may use as many `--filter` options on the command line as you like to
    build up the list of files to exclude.  If the filter contains whitespace,
    be sure to quote it so that the shell gives the rule to rsync as a single
    argument.  The text below also mentions that you can use an underscore to
    replace the space that separates a rule from its arg.

    See the [FILTER RULES](#) section for detailed information on this option.

0.  `-F`

    The `-F` option is a shorthand for adding two [`--filter`](#opt) rules to
    your command.  The first time it is used is a shorthand for this rule:

    >     --filter='dir-merge /.rsync-filter'

    This tells rsync to look for per-directory .rsync-filter files that have
    been sprinkled through the hierarchy and use their rules to filter the
    files in the transfer.  If `-F` is repeated, it is a shorthand for this
    rule:

    >     --filter='exclude .rsync-filter'

    This filters out the .rsync-filter files themselves from the transfer.

    See the [FILTER RULES](#) section for detailed information on how these
    options work.

0.  `--exclude=PATTERN`

    This option is a simplified form of the [`--filter`](#opt) option that
    specifies an exclude rule and does not allow the full rule-parsing syntax
    of normal filter rules.  This is equivalent to specifying `-f'- PATTERN'`.

    See the [FILTER RULES](#) section for detailed information on this option.

0.  `--exclude-from=FILE`

    This option is related to the [`--exclude`](#opt) option, but it specifies
    a FILE that contains exclude patterns (one per line).  Blank lines in the
    file are ignored, as are whole-line comments that start with '`;`' or '`#`'
    (filename rules that contain those characters are unaffected).

    If a line begins with "`- `" (dash, space) or "`+ `" (plus, space), then
    the type of rule is being explicitly specified as an exclude or an include
    (respectively).  Any rules without such a prefix are taken to be an exclude.

    If a line consists of just "`!`", then the current filter rules are cleared
    before adding any further rules.

    If _FILE_ is '`-`', the list will be read from standard input.

0.  `--include=PATTERN`

    This option is a simplified form of the [`--filter`](#opt) option that
    specifies an include rule and does not allow the full rule-parsing syntax
    of normal filter rules.  This is equivalent to specifying `-f'+ PATTERN'`.

    See the [FILTER RULES](#) section for detailed information on this option.

0.  `--include-from=FILE`

    This option is related to the [`--include`](#opt) option, but it specifies
    a FILE that contains include patterns (one per line).  Blank lines in the
    file are ignored, as are whole-line comments that start with '`;`' or '`#`'
    (filename rules that contain those characters are unaffected).

    If a line begins with "`- `" (dash, space) or "`+ `" (plus, space), then
    the type of rule is being explicitly specified as an exclude or an include
    (respectively).  Any rules without such a prefix are taken to be an include.

    If a line consists of just "`!`", then the current filter rules are cleared
    before adding any further rules.

    If _FILE_ is '`-`', the list will be read from standard input.

0.  `--files-from=FILE`

    Using this option allows you to specify the exact list of files to transfer
    (as read from the specified FILE or '`-`' for standard input).  It also
    tweaks the default behavior of rsync to make transferring just the
    specified files and directories easier:

    - The [`--relative`](#opt) (`-R`) option is implied, which preserves the
      path information that is specified for each item in the file (use
      `--no-relative` or `--no-R` if you want to turn that off).
    - The [`--dirs`](#opt) (`-d`) option is implied, which will create
      directories specified in the list on the destination rather than noisily
      skipping them (use `--no-dirs` or `--no-d` if you want to turn that off).
    - The [`--archive`](#opt) (`-a`) option's behavior does not imply
      [`--recursive`](#opt) (`-r`), so specify it explicitly, if you want it.
    - These side-effects change the default state of rsync, so the position of
      the `--files-from` option on the command-line has no bearing on how other
      options are parsed (e.g. [`-a`](#opt) works the same before or after
      `--files-from`, as does `--no-R` and all other options).

    The filenames that are read from the FILE are all relative to the source
    dir -- any leading slashes are removed and no ".." references are allowed
    to go higher than the source dir.  For example, take this command:

    >     rsync -a --files-from=/tmp/foo /usr remote:/backup

    If /tmp/foo contains the string "bin" (or even "/bin"), the /usr/bin
    directory will be created as /backup/bin on the remote host.  If it
    contains "bin/" (note the trailing slash), the immediate contents of the
    directory would also be sent (without needing to be explicitly mentioned in
    the file -- this began in version 2.6.4).  In both cases, if the
    [`-r`](#opt) option was enabled, that dir's entire hierarchy would also be
    transferred (keep in mind that [`-r`](#opt) needs to be specified
    explicitly with `--files-from`, since it is not implied by [`-a`](#opt).
    Also note that the effect of the (enabled by default) [`-r`](#opt) option
    is to duplicate only the path info that is read from the file -- it does
    not force the duplication of the source-spec path (/usr in this case).

    In addition, the `--files-from` file can be read from the remote host
    instead of the local host if you specify a "host:" in front of the file
    (the host must match one end of the transfer).  As a short-cut, you can
    specify just a prefix of ":" to mean "use the remote end of the transfer".
    For example:

    >     rsync -a --files-from=:/path/file-list src:/ /tmp/copy

    This would copy all the files specified in the /path/file-list file that
    was located on the remote "src" host.

    If the [`--iconv`](#opt) and [`--secluded-args`](#opt) options are specified
    and the `--files-from` filenames are being sent from one host to another,
    the filenames will be translated from the sending host's charset to the
    receiving host's charset.

    NOTE: sorting the list of files in the `--files-from` input helps rsync to
    be more efficient, as it will avoid re-visiting the path elements that are
    shared between adjacent entries.  If the input is not sorted, some path
    elements (implied directories) may end up being scanned multiple times, and
    rsync will eventually unduplicate them after they get turned into file-list
    elements.

0.  `--from0`, `-0`

    This tells rsync that the rules/filenames it reads from a file are
    terminated by a null ('\\0') character, not a NL, CR, or CR+LF.  This
    affects [`--exclude-from`](#opt), [`--include-from`](#opt),
    [`--files-from`](#opt), and any merged files specified in a
    [`--filter`](#opt) rule.  It does not affect [`--cvs-exclude`](#opt) (since
    all names read from a .cvsignore file are split on whitespace).

0. `--old-args`

    This option tells rsync to stop trying to protect the arg values on the
    remote side from unintended word-splitting or other misinterpretation.
    It also allows the client to treat an empty arg as a "." instead of
    generating an error.

    The default in a modern rsync is for "shell-active" characters (including
    spaces) to be backslash-escaped in the args that are sent to the remote
    shell.  The wildcard characters `*`, `?`, `[`, & `]` are not escaped in
    filename args (allowing them to expand into multiple filenames) while being
    protected in option args, such as [`--usermap`](#opt).

    If you have a script that wants to use old-style arg splitting in its
    filenames, specify this option once.  If the remote shell has a problem
    with any backslash escapes at all, specify this option twice.

    You may also control this setting via the [`RSYNC_OLD_ARGS`](#) environment
    variable.  If it has the value "1", rsync will default to a single-option
    setting.  If it has the value "2" (or more), rsync will default to a
    repeated-option setting.  If it is "0", you'll get the default escaping
    behavior.  The environment is always overridden by manually specified
    positive or negative options (the negative is `--no-old-args`).

    Note that this option also disables the extra safety check added in 3.2.5
    that ensures that a remote sender isn't including extra top-level items in
    the file-list that you didn't request.  This side-effect is necessary
    because we can't know for sure what names to expect when the remote shell
    is interpreting the args.

    This option conflicts with the [`--secluded-args`](#opt) option.

0.  `--secluded-args`, `-s`

    This option sends all filenames and most options to the remote rsync via
    the protocol (not the remote shell command line) which avoids letting the
    remote shell modify them.  Wildcards are expanded on the remote host by
    rsync instead of a shell.

    This is similar to the default backslash-escaping of args that was added
    in 3.2.4 (see [`--old-args`](#opt)) in that it prevents things like space
    splitting and unwanted special-character side-effects. However, it has the
    drawbacks of being incompatible with older rsync versions (prior to 3.0.0)
    and of being refused by restricted shells that want to be able to inspect
    all the option values for safety.

    This option is useful for those times that you need the argument's
    character set to be converted for the remote host, if the remote shell is
    incompatible with the default backslash-escpaing method, or there is some
    other reason that you want the majority of the options and arguments to
    bypass the command-line of the remote shell.

    If you combine this option with [`--iconv`](#opt), the args related to the
    remote side will be translated from the local to the remote character-set.
    The translation happens before wild-cards are expanded.  See also the
    [`--files-from`](#opt) option.

    You may also control this setting via the [`RSYNC_PROTECT_ARGS`](#)
    environment variable.  If it has a non-zero value, this setting will be
    enabled by default, otherwise it will be disabled by default.  Either state
    is overridden by a manually specified positive or negative version of this
    option (note that `--no-s` and `--no-secluded-args` are the negative
    versions).  This environment variable is also superseded by a non-zero
    [`RSYNC_OLD_ARGS`](#) export.

    This option conflicts with the [`--old-args`](#opt) option.

    This option used to be called `--protect-args` (before 3.2.6) and that
    older name can still be used (though specifying it as `-s` is always the
    easiest and most compatible choice).

0.  `--trust-sender`

    This option disables two extra validation checks that a local client
    performs on the file list generated by a remote sender.  This option should
    only be used if you trust the sender to not put something malicious in the
    file list (something that could possibly be done via a modified rsync, a
    modified shell, or some other similar manipulation).

    Normally, the rsync client (as of version 3.2.5) runs two extra validation
    checks when pulling files from a remote rsync:

    - It verifies that additional arg items didn't get added at the top of the
      transfer.
    - It verifies that none of the items in the file list are names that should
      have been excluded (if filter rules were specified).

    Note that various options can turn off one or both of these checks if the
    option interferes with the validation.  For instance:

    - Using a per-directory filter file reads filter rules that only the server
      knows about, so the filter checking is disabled.
    - Using the [`--old-args`](#opt) option allows the sender to manipulate the
      requested args, so the arg checking is disabled.
    - Reading the files-from list from the server side means that the client
      doesn't know the arg list, so the arg checking is disabled.
    - Using [`--read-batch`](#opt) disables both checks since the batch file's
      contents will have been verified when it was created.

    This option may help an under-powered client server if the extra pattern
    matching is slowing things down on a huge transfer.  It can also be used to
    work around a currently-unknown bug in the verification logic for a transfer
    from a trusted sender.

    When using this option it is a good idea to specify a dedicated destination
    directory, as discussed in the [MULTI-HOST SECURITY](#) section.

0.  `--copy-as=USER[:GROUP]`

    This option instructs rsync to use the USER and (if specified after a
    colon) the GROUP for the copy operations.  This only works if the user that
    is running rsync has the ability to change users.  If the group is not
    specified then the user's default groups are used.

    This option can help to reduce the risk of an rsync being run as root into
    or out of a directory that might have live changes happening to it and you
    want to make sure that root-level read or write actions of system files are
    not possible.  While you could alternatively run all of rsync as the
    specified user, sometimes you need the root-level host-access credentials
    to be used, so this allows rsync to drop root for the copying part of the
    operation after the remote-shell or daemon connection is established.

    The option only affects one side of the transfer unless the transfer is
    local, in which case it affects both sides.  Use the
    [`--remote-option`](#opt) to affect the remote side, such as
    `-M--copy-as=joe`.  For a local transfer, the lsh (or lsh.sh) support file
    provides a local-shell helper script that can be used to allow a
    "localhost:" or "lh:" host-spec to be specified without needing to setup
    any remote shells, allowing you to specify remote options that affect the
    side of the transfer that is using the host-spec (and using hostname "lh"
    avoids the overriding of the remote directory to the user's home dir).

    For example, the following rsync writes the local files as user "joe":

    >     sudo rsync -aiv --copy-as=joe host1:backups/joe/ /home/joe/

    This makes all files owned by user "joe", limits the groups to those that
    are available to that user, and makes it impossible for the joe user to do
    a timed exploit of the path to induce a change to a file that the joe user
    has no permissions to change.

    The following command does a local copy into the "dest/" dir as user "joe"
    (assuming you've installed support/lsh into a dir on your $PATH):

    >     sudo rsync -aive lsh -M--copy-as=joe src/ lh:dest/

0.  `--temp-dir=DIR`, `-T`

    This option instructs rsync to use DIR as a scratch directory when creating
    temporary copies of the files transferred on the receiving side.  The
    default behavior is to create each temporary file in the same directory as
    the associated destination file.  Beginning with rsync 3.1.1, the temp-file
    names inside the specified DIR will not be prefixed with an extra dot
    (though they will still have a random suffix added).

    This option is most often used when the receiving disk partition does not
    have enough free space to hold a copy of the largest file in the transfer.
    In this case (i.e. when the scratch directory is on a different disk
    partition), rsync will not be able to rename each received temporary file
    over the top of the associated destination file, but instead must copy it
    into place.  Rsync does this by copying the file over the top of the
    destination file, which means that the destination file will contain
    truncated data during this copy.  If this were not done this way (even if
    the destination file were first removed, the data locally copied to a
    temporary file in the destination directory, and then renamed into place)
    it would be possible for the old file to continue taking up disk space (if
    someone had it open), and thus there might not be enough room to fit the
    new version on the disk at the same time.

    If you are using this option for reasons other than a shortage of disk
    space, you may wish to combine it with the [`--delay-updates`](#opt)
    option, which will ensure that all copied files get put into subdirectories
    in the destination hierarchy, awaiting the end of the transfer.  If you
    don't have enough room to duplicate all the arriving files on the
    destination partition, another way to tell rsync that you aren't overly
    concerned about disk space is to use the [`--partial-dir`](#opt) option
    with a relative path; because this tells rsync that it is OK to stash off a
    copy of a single file in a subdir in the destination hierarchy, rsync will
    use the partial-dir as a staging area to bring over the copied file, and
    then rename it into place from there. (Specifying a [`--partial-dir`](#opt)
    with an absolute path does not have this side-effect.)

0.  `--fuzzy`, `-y`

    This option tells rsync that it should look for a basis file for any
    destination file that is missing.  The current algorithm looks in the same
    directory as the destination file for either a file that has an identical
    size and modified-time, or a similarly-named file.  If found, rsync uses
    the fuzzy basis file to try to speed up the transfer.

    If the option is repeated, the fuzzy scan will also be done in any matching
    alternate destination directories that are specified via
    [`--compare-dest`](#opt), [`--copy-dest`](#opt), or [`--link-dest`](#opt).

    Note that the use of the [`--delete`](#opt) option might get rid of any
    potential fuzzy-match files, so either use [`--delete-after`](#opt) or
    specify some filename exclusions if you need to prevent this.

0.  `--compare-dest=DIR`

    This option instructs rsync to use _DIR_ on the destination machine as an
    additional hierarchy to compare destination files against doing transfers
    (if the files are missing in the destination directory).  If a file is
    found in _DIR_ that is identical to the sender's file, the file will NOT be
    transferred to the destination directory.  This is useful for creating a
    sparse backup of just files that have changed from an earlier backup.  This
    option is typically used to copy into an empty (or newly created)
    directory.

    Beginning in version 2.6.4, multiple `--compare-dest` directories may be
    provided, which will cause rsync to search the list in the order specified
    for an exact match.  If a match is found that differs only in attributes, a
    local copy is made and the attributes updated.  If a match is not found, a
    basis file from one of the _DIRs_ will be selected to try to speed up the
    transfer.

    If _DIR_ is a relative path, it is relative to the destination directory.
    See also [`--copy-dest`](#opt) and [`--link-dest`](#opt).

    NOTE: beginning with version 3.1.0, rsync will remove a file from a
    non-empty destination hierarchy if an exact match is found in one of the
    compare-dest hierarchies (making the end result more closely match a fresh
    copy).

0.  `--copy-dest=DIR`

    This option behaves like [`--compare-dest`](#opt), but rsync will also copy
    unchanged files found in _DIR_ to the destination directory using a local
    copy.  This is useful for doing transfers to a new destination while
    leaving existing files intact, and then doing a flash-cutover when all
    files have been successfully transferred.

    Multiple `--copy-dest` directories may be provided, which will cause rsync
    to search the list in the order specified for an unchanged file.  If a
    match is not found, a basis file from one of the _DIRs_ will be selected to
    try to speed up the transfer.

    If _DIR_ is a relative path, it is relative to the destination directory.
    See also [`--compare-dest`](#opt) and [`--link-dest`](#opt).

0.  `--link-dest=DIR`

    This option behaves like [`--copy-dest`](#opt), but unchanged files are
    hard linked from _DIR_ to the destination directory.  The files must be
    identical in all preserved attributes (e.g. permissions, possibly
    ownership) in order for the files to be linked together.  An example:

    >     rsync -av --link-dest=$PWD/prior_dir host:src_dir/ new_dir/

    If files aren't linking, double-check their attributes.  Also check if
    some attributes are getting forced outside of rsync's control, such a mount
    option that squishes root to a single user, or mounts a removable drive
    with generic ownership (such as OS X's "Ignore ownership on this volume"
    option).

    Beginning in version 2.6.4, multiple `--link-dest` directories may be
    provided, which will cause rsync to search the list in the order specified
    for an exact match (there is a limit of 20 such directories).  If a match
    is found that differs only in attributes, a local copy is made and the
    attributes updated.  If a match is not found, a basis file from one of the
    _DIRs_ will be selected to try to speed up the transfer.

    This option works best when copying into an empty destination hierarchy, as
    existing files may get their attributes tweaked, and that can affect
    alternate destination files via hard-links.  Also, itemizing of changes can
    get a bit muddled.  Note that prior to version 3.1.0, an
    alternate-directory exact match would never be found (nor linked into the
    destination) when a destination file already exists.

    Note that if you combine this option with [`--ignore-times`](#opt), rsync will not
    link any files together because it only links identical files together as a
    substitute for transferring the file, never as an additional check after
    the file is updated.

    If _DIR_ is a relative path, it is relative to the destination directory.
    See also [`--compare-dest`](#opt) and [`--copy-dest`](#opt).

    Note that rsync versions prior to 2.6.1 had a bug that could prevent
    `--link-dest` from working properly for a non-super-user when
    [`--owner`](#opt) (`-o`) was specified (or implied).  You can work-around
    this bug by avoiding the `-o` option (or using `--no-o`) when sending to an
    old rsync.

0.  `--compress`, `-z`

    With this option, rsync compresses the file data as it is sent to the
    destination machine, which reduces the amount of data being transmitted --
    something that is useful over a slow connection.

    Rsync supports multiple compression methods and will choose one for you
    unless you force the choice using the [`--compress-choice`](#opt) (`--zc`)
    option.

    Run `rsync --version` to see the default compress list compiled into your
    version.

    When both sides of the transfer are at least 3.2.0, rsync chooses the first
    algorithm in the client's list of choices that is also in the server's list
    of choices.  If no common compress choice is found, rsync exits with
    an error.  If the remote rsync is too old to support checksum negotiation,
    its list is assumed to be "zlib".

    The default order can be customized by setting the environment variable
    [`RSYNC_COMPRESS_LIST`](#) to a space-separated list of acceptable
    compression names.  If the string contains a "`&`" character, it is
    separated into the "client string & server string", otherwise the same
    string applies to both.  If the string (or string portion) contains no
    non-whitespace characters, the default compress list is used.  Any unknown
    compression names are discarded from the list, but a list with only invalid
    names results in a failed negotiation.

    There are some older rsync versions that were configured to reject a `-z`
    option and require the use of `-zz` because their compression library was
    not compatible with the default zlib compression method.  You can usually
    ignore this weirdness unless the rsync server complains and tells you to
    specify `-zz`.

0.  `--compress-choice=STR`, `--zc=STR`

    This option can be used to override the automatic negotiation of the
    compression algorithm that occurs when [`--compress`](#opt) is used.  The
    option implies [`--compress`](#opt) unless "none" was specified, which
    instead implies `--no-compress`.

    The compression options that you may be able to use are:

    - `zstd`
    - `lz4`
    - `zlibx`
    - `zlib`
    - `none`

    Run `rsync --version` to see the default compress list compiled into your
    version (which may differ from the list above).

    Note that if you see an error about an option named `--old-compress` or
    `--new-compress`, this is rsync trying to send the `--compress-choice=zlib`
    or `--compress-choice=zlibx` option in a backward-compatible manner that
    more rsync versions understand.  This error indicates that the older rsync
    version on the server will not allow you to force the compression type.

    Note that the "zlibx" compression algorithm is just the "zlib" algorithm
    with matched data excluded from the compression stream (to try to make it
    more compatible with an external zlib implementation).

0.  `--compress-level=NUM`, `--zl=NUM`

    Explicitly set the compression level to use (see [`--compress`](#opt),
    `-z`) instead of letting it default.  The [`--compress`](#opt) option is
    implied as long as the level chosen is not a "don't compress" level for the
    compression algorithm that is in effect (e.g. zlib compression treats level
    0 as "off").

    The level values vary depending on the checksum in effect.  Because rsync
    will negotiate a checksum choice by default (when the remote rsync is new
    enough), it can be good to combine this option with a
    [`--compress-choice`](#opt) (`--zc`) option unless you're sure of the
    choice in effect.  For example:

    >     rsync -aiv --zc=zstd --zl=22 host:src/ dest/

    For zlib & zlibx compression the valid values are from 1 to 9 with 6 being
    the default.  Specifying `--zl=0` turns compression off, and specifying
    `--zl=-1` chooses the default level of 6.

    For zstd compression the valid values are from -131072 to 22 with 3 being
    the default. Specifying 0 chooses the default of 3.

    For lz4 compression there are no levels, so the value is always 0.

    If you specify a too-large or too-small value, the number is silently
    limited to a valid value.  This allows you to specify something like
    `--zl=999999999` and be assured that you'll end up with the maximum
    compression level no matter what algorithm was chosen.

    If you want to know the compression level that is in effect, specify
    [`--debug=nstr`](#opt) to see the "negotiated string" results.  This will
    report something like "`Client compress: zstd (level 3)`" (along with the
    checksum choice in effect).

0.  `--skip-compress=LIST`

    **NOTE:** no compression method currently supports per-file compression
    changes, so this option has no effect.

    Override the list of file suffixes that will be compressed as little as
    possible.  Rsync sets the compression level on a per-file basis based on
    the file's suffix.  If the compression algorithm has an "off" level, then
    no compression occurs for those files.  Other algorithms that support
    changing the streaming level on-the-fly will have the level minimized to
    reduces the CPU usage as much as possible for a matching file.

    The **LIST** should be one or more file suffixes (without the dot) separated
    by slashes (`/`).  You may specify an empty string to indicate that no files
    should be skipped.

    Simple character-class matching is supported: each must consist of a list
    of letters inside the square brackets (e.g. no special classes, such as
    "[:alpha:]", are supported, and '-' has no special meaning).

    The characters asterisk (`*`) and question-mark (`?`) have no special meaning.

    Here's an example that specifies 6 suffixes to skip (since 1 of the 5 rules
    matches 2 suffixes):

    >     --skip-compress=gz/jpg/mp[34]/7z/bz2

    The default file suffixes in the skip-compress list in this version of
    rsync are:

    [comment]: # (This list gets used for the default-dont-compress.h file.)

    > 3g2
    > 3gp
    > 7z
    > aac
    > ace
    > apk
    > avi
    > bz2
    > deb
    > dmg
    > ear
    > f4v
    > flac
    > flv
    > gpg
    > gz
    > iso
    > jar
    > jpeg
    > jpg
    > lrz
    > lz
    > lz4
    > lzma
    > lzo
    > m1a
    > m1v
    > m2a
    > m2ts
    > m2v
    > m4a
    > m4b
    > m4p
    > m4r
    > m4v
    > mka
    > mkv
    > mov
    > mp1
    > mp2
    > mp3
    > mp4
    > mpa
    > mpeg
    > mpg
    > mpv
    > mts
    > odb
    > odf
    > odg
    > odi
    > odm
    > odp
    > ods
    > odt
    > oga
    > ogg
    > ogm
    > ogv
    > ogx
    > opus
    > otg
    > oth
    > otp
    > ots
    > ott
    > oxt
    > png
    > qt
    > rar
    > rpm
    > rz
    > rzip
    > spx
    > squashfs
    > sxc
    > sxd
    > sxg
    > sxm
    > sxw
    > sz
    > tbz
    > tbz2
    > tgz
    > tlz
    > ts
    > txz
    > tzo
    > vob
    > war
    > webm
    > webp
    > xz
    > z
    > zip
    > zst

    This list will be replaced by your `--skip-compress` list in all but one
    situation: a copy from a daemon rsync will add your skipped suffixes to its
    list of non-compressing files (and its list may be configured to a
    different default).

0.  `--numeric-ids`

    With this option rsync will transfer numeric group and user IDs rather than
    using user and group names and mapping them at both ends.

    By default rsync will use the username and groupname to determine what
    ownership to give files.  The special uid 0 and the special group 0 are
    never mapped via user/group names even if the `--numeric-ids` option is not
    specified.

    If a user or group has no name on the source system or it has no match on
    the destination system, then the numeric ID from the source system is used
    instead.  See also the [`use chroot`](rsyncd.conf.5#use_chroot) setting
    in the rsyncd.conf manpage for some comments on how the chroot setting
    affects rsync's ability to look up the names of the users and groups and
    what you can do about it.

0.  `--usermap=STRING`, `--groupmap=STRING`

    These options allow you to specify users and groups that should be mapped
    to other values by the receiving side.  The **STRING** is one or more
    **FROM**:**TO** pairs of values separated by commas.  Any matching **FROM**
    value from the sender is replaced with a **TO** value from the receiver.
    You may specify usernames or user IDs for the **FROM** and **TO** values,
    and the **FROM** value may also be a wild-card string, which will be
    matched against the sender's names (wild-cards do NOT match against ID
    numbers, though see below for why a '`*`' matches everything).  You may
    instead specify a range of ID numbers via an inclusive range: LOW-HIGH.
    For example:

    >     --usermap=0-99:nobody,wayne:admin,*:normal --groupmap=usr:1,1:usr

    The first match in the list is the one that is used.  You should specify
    all your user mappings using a single `--usermap` option, and/or all your
    group mappings using a single `--groupmap` option.

    Note that the sender's name for the 0 user and group are not transmitted to
    the receiver, so you should either match these values using a 0, or use the
    names in effect on the receiving side (typically "root").  All other
    **FROM** names match those in use on the sending side.  All **TO** names
    match those in use on the receiving side.

    Any IDs that do not have a name on the sending side are treated as having
    an empty name for the purpose of matching.  This allows them to be matched
    via a "`*`" or using an empty name.  For instance:

    >     --usermap=:nobody --groupmap=*:nobody

    When the [`--numeric-ids`](#opt) option is used, the sender does not send any
    names, so all the IDs are treated as having an empty name.  This means that
    you will need to specify numeric **FROM** values if you want to map these
    nameless IDs to different values.

    For the `--usermap` option to work, the receiver will need to be running as
    a super-user (see also the [`--super`](#opt) and [`--fake-super`](#opt)
    options).  For the `--groupmap` option to work, the receiver will need to
    have permissions to set that group.

    Starting with rsync 3.2.4, the `--usermap` option implies the
    [`--owner`](#opt) (`-o`) option while the `--groupmap` option implies the
    [`--group`](#opt) (`-g`) option (since rsync needs to have those options
    enabled for the mapping options to work).

    An older rsync client may need to use [`-s`](#opt) to avoid a complaint
    about wildcard characters, but a modern rsync handles this automatically.

0.  `--chown=USER:GROUP`

    This option forces all files to be owned by USER with group GROUP.  This is
    a simpler interface than using [`--usermap`](#opt) & [`--groupmap`](#opt)
    directly, but it is implemented using those options internally so they
    cannot be mixed.  If either the USER or GROUP is empty, no mapping for the
    omitted user/group will occur.  If GROUP is empty, the trailing colon may
    be omitted, but if USER is empty, a leading colon must be supplied.

    If you specify "`--chown=foo:bar`", this is exactly the same as specifying
    "`--usermap=*:foo --groupmap=*:bar`", only easier (and with the same
    implied [`--owner`](#opt) and/or [`--group`](#opt) options).

    An older rsync client may need to use [`-s`](#opt) to avoid a complaint
    about wildcard characters, but a modern rsync handles this automatically.

0.  `--timeout=SECONDS`

    This option allows you to set a maximum I/O timeout in seconds.  If no data
    is transferred for the specified time then rsync will exit.  The default is
    0, which means no timeout.

0.  `--contimeout=SECONDS`

    This option allows you to set the amount of time that rsync will wait for
    its connection to an rsync daemon to succeed.  If the timeout is reached,
    rsync exits with an error.

0.  `--address=ADDRESS`

    By default rsync will bind to the wildcard address when connecting to an
    rsync daemon.  The `--address` option allows you to specify a specific IP
    address (or hostname) to bind to.

    See also [the daemon version of the `--address` option](#dopt--address).

0.  `--port=PORT`

    This specifies an alternate TCP port number to use rather than the default
    of 873.  This is only needed if you are using the double-colon (::) syntax
    to connect with an rsync daemon (since the URL syntax has a way to specify
    the port as a part of the URL).

    See also [the daemon version of the `--port` option](#dopt--port).

0.  `--sockopts=OPTIONS`

    This option can provide endless fun for people who like to tune their
    systems to the utmost degree.  You can set all sorts of socket options
    which may make transfers faster (or slower!).  Read the manpage for the
    `setsockopt()` system call for details on some of the options you may be
    able to set.  By default no special socket options are set.  This only
    affects direct socket connections to a remote rsync daemon.

    See also [the daemon version of the `--sockopts` option](#dopt--sockopts).

0.  `--blocking-io`

    This tells rsync to use blocking I/O when launching a remote shell
    transport.  If the remote shell is either rsh or remsh, rsync defaults to
    using blocking I/O, otherwise it defaults to using non-blocking I/O. (Note
    that ssh prefers non-blocking I/O.)

0.  `--outbuf=MODE`

    This sets the output buffering mode.  The mode can be None (aka
    Unbuffered), Line, or Block (aka Full).  You may specify as little as a
    single letter for the mode, and use upper or lower case.

    The main use of this option is to change Full buffering to Line buffering
    when rsync's output is going to a file or pipe.

0.  `--itemize-changes`, `-i`

    Requests a simple itemized list of the changes that are being made to each
    file, including attribute changes.  This is exactly the same as specifying
    [`--out-format='%i %n%L'`](#opt).  If you repeat the option, unchanged
    files will also be output, but only if the receiving rsync is at least
    version 2.6.7 (you can use `-vv` with older versions of rsync, but that
    also turns on the output of other verbose messages).

    The "%i" escape has a cryptic output that is 11 letters long.  The general
    format is like the string `YXcstpoguax`, where **Y** is replaced by the type
    of update being done, **X** is replaced by the file-type, and the other
    letters represent attributes that may be output if they are being modified.

    The update types that replace the **Y** are as follows:

    - A `<` means that a file is being transferred to the remote host (sent).
    - A `>` means that a file is being transferred to the local host
      (received).
    - A `c` means that a local change/creation is occurring for the item (such
      as the creation of a directory or the changing of a symlink, etc.).
    - A `h` means that the item is a hard link to another item (requires
      [`--hard-links`](#opt)).
    - A `.` means that the item is not being updated (though it might have
      attributes that are being modified).
    - A `*` means that the rest of the itemized-output area contains a message
      (e.g. "deleting").

    The file-types that replace the **X** are: `f` for a file, a `d` for a
    directory, an `L` for a symlink, a `D` for a device, and a `S` for a
    special file (e.g. named sockets and fifos).

    The other letters in the string indicate if some attributes of the file
    have changed, as follows:

    - "`.`" - the attribute is unchanged.
    - "`+`" - the file is newly created.
    - "` `" - all the attributes are unchanged (all dots turn to spaces).
    - "`?`" - the change is unknown (when the remote rsync is old).
    - A letter indicates an attribute is being updated.

    The attribute that is associated with each letter is as follows:

    - A `c` means either that a regular file has a different checksum (requires
      [`--checksum`](#opt)) or that a symlink, device, or special file has a
      changed value.  Note that if you are sending files to an rsync prior to
      3.0.1, this change flag will be present only for checksum-differing
      regular files.
    - A `s` means the size of a regular file is different and will be updated
      by the file transfer.
    - A `t` means the modification time is different and is being updated to
      the sender's value (requires [`--times`](#opt)).  An alternate value of
      `T` means that the modification time will be set to the transfer time,
      which happens when a file/symlink/device is updated without
      [`--times`](#opt) and when a symlink is changed and the receiver can't
      set its time. (Note: when using an rsync 3.0.0 client, you might see the
      `s` flag combined with `t` instead of the proper `T` flag for this
      time-setting failure.)
    - A `p` means the permissions are different and are being updated to the
      sender's value (requires [`--perms`](#opt)).
    - An `o` means the owner is different and is being updated to the sender's
      value (requires [`--owner`](#opt) and super-user privileges).
    - A `g` means the group is different and is being updated to the sender's
      value (requires [`--group`](#opt) and the authority to set the group).
    - A `u`|`n`|`b` indicates the following information:
      - `u`  means the access (use) time is different and is being updated to
        the sender's value (requires [`--atimes`](#opt))
      - `n` means the create time (newness) is different and is being updated
        to the sender's value (requires [`--crtimes`](#opt))
      - `b` means that both the access and create times are being updated
    - The `a` means that the ACL information is being changed.
    - The `x` means that the extended attribute information is being changed.

    One other output is possible: when deleting files, the "%i" will output the
    string "`*deleting`" for each item that is being removed (assuming that you
    are talking to a recent enough rsync that it logs deletions instead of
    outputting them as a verbose message).

0.  `--out-format=FORMAT`

    This allows you to specify exactly what the rsync client outputs to the
    user on a per-update basis.  The format is a text string containing
    embedded single-character escape sequences prefixed with a percent (%)
    character.  A default format of "%n%L" is assumed if either
    [`--info=name`](#opt) or [`-v`](#opt) is specified (this tells you just the
    name of the file and, if the item is a link, where it points).  For a full
    list of the possible escape characters, see the [`log
    format`](rsyncd.conf.5#log_format) setting in the rsyncd.conf manpage.

    Specifying the `--out-format` option implies the [`--info=name`](#opt)
    option, which will mention each file, dir, etc. that gets updated in a
    significant way (a transferred file, a recreated symlink/device, or a
    touched directory).  In addition, if the itemize-changes escape (%i) is
    included in the string (e.g. if the [`--itemize-changes`](#opt) option was
    used), the logging of names increases to mention any item that is changed
    in any way (as long as the receiving side is at least 2.6.4).  See the
    [`--itemize-changes`](#opt) option for a description of the output of "%i".

    Rsync will output the out-format string prior to a file's transfer unless
    one of the transfer-statistic escapes is requested, in which case the
    logging is done at the end of the file's transfer.  When this late logging
    is in effect and [`--progress`](#opt) is also specified, rsync will also
    output the name of the file being transferred prior to its progress
    information (followed, of course, by the out-format output).

0.  `--log-file=FILE`

    This option causes rsync to log what it is doing to a file.  This is
    similar to the logging that a daemon does, but can be requested for the
    client side and/or the server side of a non-daemon transfer.  If specified
    as a client option, transfer logging will be enabled with a default format
    of "%i %n%L".  See the [`--log-file-format`](#opt) option if you wish to
    override this.

    Here's an example command that requests the remote side to log what is
    happening:

    >     rsync -av --remote-option=--log-file=/tmp/rlog src/ dest/

    This is very useful if you need to debug why a connection is closing
    unexpectedly.

    See also [the daemon version of the `--log-file` option](#dopt--log-file).

0.  `--log-file-format=FORMAT`

    This allows you to specify exactly what per-update logging is put into the
    file specified by the [`--log-file`](#opt) option (which must also be
    specified for this option to have any effect).  If you specify an empty
    string, updated files will not be mentioned in the log file.  For a list of
    the possible escape characters, see the [`log format`](rsyncd.conf.5#log_format)
    setting in the rsyncd.conf manpage.

    The default FORMAT used if [`--log-file`](#opt) is specified and this
    option is not is '%i %n%L'.

    See also [the daemon version of the `--log-file-format`
    option](#dopt--log-file-format).

0.  `--stats`

    This tells rsync to print a verbose set of statistics on the file transfer,
    allowing you to tell how effective rsync's delta-transfer algorithm is for
    your data.  This option is equivalent to [`--info=stats2`](#opt) if
    combined with 0 or 1 [`-v`](#opt) options, or [`--info=stats3`](#opt) if
    combined with 2 or more [`-v`](#opt) options.

    The current statistics are as follows:

    - `Number of files` is the count of all "files" (in the generic sense),
      which includes directories, symlinks, etc.  The total count will be
      followed by a list of counts by filetype (if the total is non-zero).  For
      example: "(reg: 5, dir: 3, link: 2, dev: 1, special: 1)" lists the totals
      for regular files, directories, symlinks, devices, and special files.  If
      any of value is 0, it is completely omitted from the list.
    - `Number of created files` is the count of how many "files" (generic
      sense) were created (as opposed to updated).  The total count will be
      followed by a list of counts by filetype (if the total is non-zero).
    - `Number of deleted files` is the count of how many "files" (generic
      sense) were deleted.  The total count will be
      followed by a list of counts by filetype (if the total is non-zero).
      Note that this line is only output if deletions are in effect, and only
      if protocol 31 is being used (the default for rsync 3.1.x).
    - `Number of regular files transferred` is the count of normal files that
      were updated via rsync's delta-transfer algorithm, which does not include
      dirs, symlinks, etc.  Note that rsync 3.1.0 added the word "regular" into
      this heading.
    - `Total file size` is the total sum of all file sizes in the transfer.
      This does not count any size for directories or special files, but does
      include the size of symlinks.
    - `Total transferred file size` is the total sum of all files sizes for
      just the transferred files.
    - `Literal data` is how much unmatched file-update data we had to send to
      the receiver for it to recreate the updated files.
    - `Matched data` is how much data the receiver got locally when recreating
      the updated files.
    - `File list size` is how big the file-list data was when the sender sent
      it to the receiver.  This is smaller than the in-memory size for the file
      list due to some compressing of duplicated data when rsync sends the
      list.
    - `File list generation time` is the number of seconds that the sender
      spent creating the file list.  This requires a modern rsync on the
      sending side for this to be present.
    - `File list transfer time` is the number of seconds that the sender spent
      sending the file list to the receiver.
    - `Total bytes sent` is the count of all the bytes that rsync sent from the
      client side to the server side.
    - `Total bytes received` is the count of all non-message bytes that rsync
      received by the client side from the server side. "Non-message" bytes
      means that we don't count the bytes for a verbose message that the server
      sent to us, which makes the stats more consistent.

0.  `--8-bit-output`, `-8`

    This tells rsync to leave all high-bit characters unescaped in the output
    instead of trying to test them to see if they're valid in the current
    locale and escaping the invalid ones.  All control characters (but never
    tabs) are always escaped, regardless of this option's setting.

    The escape idiom that started in 2.6.7 is to output a literal backslash
    (`\`) and a hash (`#`), followed by exactly 3 octal digits.  For example, a
    newline would output as "`\#012`".  A literal backslash that is in a
    filename is not escaped unless it is followed by a hash and 3 digits (0-9).

0.  `--human-readable`, `-h`

    Output numbers in a more human-readable format.  There are 3 possible levels:

    1. output numbers with a separator between each set of 3 digits (either a
       comma or a period, depending on if the decimal point is represented by a
       period or a comma).
    2. output numbers in units of 1000 (with a character suffix for larger
       units -- see below).
    3. output numbers in units of 1024.

    The default is human-readable level 1.  Each `-h` option increases the
    level by one.  You can take the level down to 0 (to output numbers as pure
    digits) by specifying the `--no-human-readable` (`--no-h`) option.

    The unit letters that are appended in levels 2 and 3 are: `K` (kilo), `M`
    (mega), `G` (giga), `T` (tera), or `P` (peta).  For example, a 1234567-byte
    file would output as 1.23M in level-2 (assuming that a period is your local
    decimal point).

    Backward compatibility note: versions of rsync prior to 3.1.0 do not
    support human-readable level 1, and they default to level 0.  Thus,
    specifying one or two `-h` options will behave in a comparable manner in
    old and new versions as long as you didn't specify a `--no-h` option prior
    to one or more `-h` options.  See the [`--list-only`](#opt) option for one
    difference.

0.  `--partial`

    By default, rsync will delete any partially transferred file if the
    transfer is interrupted.  In some circumstances it is more desirable to
    keep partially transferred files.  Using the `--partial` option tells rsync
    to keep the partial file which should make a subsequent transfer of the
    rest of the file much faster.

0.  `--partial-dir=DIR`

    This option modifies the behavior of the [`--partial`](#opt) option while
    also implying that it be enabled.  This enhanced partial-file method puts
    any partially transferred files into the specified _DIR_ instead of writing
    the partial file out to the destination file.  On the next transfer, rsync
    will use a file found in this dir as data to speed up the resumption of the
    transfer and then delete it after it has served its purpose.

    Note that if [`--whole-file`](#opt) is specified (or implied), any
    partial-dir files that are found for a file that is being updated will
    simply be removed (since rsync is sending files without using rsync's
    delta-transfer algorithm).

    Rsync will create the _DIR_ if it is missing, but just the last dir -- not
    the whole path.  This makes it easy to use a relative path (such as
    "`--partial-dir=.rsync-partial`") to have rsync create the
    partial-directory in the destination file's directory when it is needed,
    and then remove it again when the partial file is deleted.  Note that this
    directory removal is only done for a relative pathname, as it is expected
    that an absolute path is to a directory that is reserved for partial-dir
    work.

    If the partial-dir value is not an absolute path, rsync will add an exclude
    rule at the end of all your existing excludes.  This will prevent the
    sending of any partial-dir files that may exist on the sending side, and
    will also prevent the untimely deletion of partial-dir items on the
    receiving side.  An example: the above `--partial-dir` option would add the
    equivalent of this "perishable" exclude at the end of any other filter
    rules: `-f '-p .rsync-partial/'`

    If you are supplying your own exclude rules, you may need to add your own
    exclude/hide/protect rule for the partial-dir because:

    1. the auto-added rule may be ineffective at the end of your other rules, or
    2. you may wish to override rsync's exclude choice.

    For instance, if you want to make rsync clean-up any left-over partial-dirs
    that may be lying around, you should specify [`--delete-after`](#opt) and
    add a "risk" filter rule, e.g.  `-f 'R .rsync-partial/'`. Avoid using
    [`--delete-before`](#opt) or [`--delete-during`](#opt) unless you don't
    need rsync to use any of the left-over partial-dir data during the current
    run.

    IMPORTANT: the `--partial-dir` should not be writable by other users or it
    is a security risk!  E.g. AVOID "/tmp"!

    You can also set the partial-dir value the [`RSYNC_PARTIAL_DIR`](#)
    environment variable.  Setting this in the environment does not force
    [`--partial`](#opt) to be enabled, but rather it affects where partial
    files go when [`--partial`](#opt) is specified.  For instance, instead of
    using `--partial-dir=.rsync-tmp` along with [`--progress`](#opt), you could
    set [`RSYNC_PARTIAL_DIR=.rsync-tmp`](#) in your environment and then use
    the [`-P`](#opt) option to turn on the use of the .rsync-tmp dir for
    partial transfers.  The only times that the [`--partial`](#opt) option does
    not look for this environment value are:

    1. when [`--inplace`](#opt) was specified (since [`--inplace`](#opt)
       conflicts with `--partial-dir`), and
    2. when [`--delay-updates`](#opt) was specified (see below).

    When a modern rsync resumes the transfer of a file in the partial-dir, that
    partial file is now updated in-place instead of creating yet another
    tmp-file copy (so it maxes out at dest + tmp instead of dest + partial +
    tmp).  This requires both ends of the transfer to be at least version
    3.2.0.

    For the purposes of the daemon-config's "`refuse options`" setting,
    `--partial-dir` does _not_ imply [`--partial`](#opt).  This is so that a
    refusal of the [`--partial`](#opt) option can be used to disallow the
    overwriting of destination files with a partial transfer, while still
    allowing the safer idiom provided by `--partial-dir`.

0.  `--delay-updates`

    This option puts the temporary file from each updated file into a holding
    directory until the end of the transfer, at which time all the files are
    renamed into place in rapid succession.  This attempts to make the updating
    of the files a little more atomic.  By default the files are placed into a
    directory named `.~tmp~` in each file's destination directory, but if
    you've specified the [`--partial-dir`](#opt) option, that directory will be
    used instead.  See the comments in the [`--partial-dir`](#opt) section for
    a discussion of how this `.~tmp~` dir will be excluded from the transfer,
    and what you can do if you want rsync to cleanup old `.~tmp~` dirs that
    might be lying around.  Conflicts with [`--inplace`](#opt) and
    [`--append`](#opt).

    This option implies [`--no-inc-recursive`](#opt) since it needs the full
    file list in memory in order to be able to iterate over it at the end.

    This option uses more memory on the receiving side (one bit per file
    transferred) and also requires enough free disk space on the receiving side
    to hold an additional copy of all the updated files.  Note also that you
    should not use an absolute path to [`--partial-dir`](#opt) unless:

    1. there is no chance of any of the files in the transfer having the same
       name (since all the updated files will be put into a single directory if
       the path is absolute), and
    2. there are no mount points in the hierarchy (since the delayed updates
       will fail if they can't be renamed into place).

    See also the "atomic-rsync" python script in the "support" subdir for an
    update algorithm that is even more atomic (it uses [`--link-dest`](#opt)
    and a parallel hierarchy of files).

0.  `--prune-empty-dirs`, `-m`

    This option tells the receiving rsync to get rid of empty directories from
    the file-list, including nested directories that have no non-directory
    children.  This is useful for avoiding the creation of a bunch of useless
    directories when the sending rsync is recursively scanning a hierarchy of
    files using include/exclude/filter rules.

    This option can still leave empty directories on the receiving side if you
    make use of [TRANSFER_RULES](#).

    Because the file-list is actually being pruned, this option also affects
    what directories get deleted when a delete is active.  However, keep in
    mind that excluded files and directories can prevent existing items from
    being deleted due to an exclude both hiding source files and protecting
    destination files.  See the perishable filter-rule option for how to avoid
    this.

    You can prevent the pruning of certain empty directories from the file-list
    by using a global "protect" filter.  For instance, this option would ensure
    that the directory "emptydir" was kept in the file-list:

    >     --filter 'protect emptydir/'

    Here's an example that copies all .pdf files in a hierarchy, only creating
    the necessary destination directories to hold the .pdf files, and ensures
    that any superfluous files and directories in the destination are removed
    (note the hide filter of non-directories being used instead of an exclude):

    >     rsync -avm --del --include='*.pdf' -f 'hide,! */' src/ dest

    If you didn't want to remove superfluous destination files, the more
    time-honored options of `--include='*/' --exclude='*'` would work
    fine in place of the hide-filter (if that is more natural to you).

0.  `--progress`

    This option tells rsync to print information showing the progress of the
    transfer.  This gives a bored user something to watch.  With a modern rsync
    this is the same as specifying [`--info=flist2,name,progress`](#opt), but
    any user-supplied settings for those info flags takes precedence (e.g.
    [`--info=flist0 --progress`](#opt)).

    While rsync is transferring a regular file, it updates a progress line that
    looks like this:

    >     782448  63%  110.64kB/s    0:00:04

    In this example, the receiver has reconstructed 782448 bytes or 63% of the
    sender's file, which is being reconstructed at a rate of 110.64 kilobytes
    per second, and the transfer will finish in 4 seconds if the current rate
    is maintained until the end.

    These statistics can be misleading if rsync's delta-transfer algorithm is
    in use.  For example, if the sender's file consists of the basis file
    followed by additional data, the reported rate will probably drop
    dramatically when the receiver gets to the literal data, and the transfer
    will probably take much longer to finish than the receiver estimated as it
    was finishing the matched part of the file.

    When the file transfer finishes, rsync replaces the progress line with a
    summary line that looks like this:

    >     1,238,099 100%  146.38kB/s    0:00:08  (xfr#5, to-chk=169/396)

    In this example, the file was 1,238,099 bytes long in total, the average
    rate of transfer for the whole file was 146.38 kilobytes per second over
    the 8 seconds that it took to complete, it was the 5th transfer of a
    regular file during the current rsync session, and there are 169 more files
    for the receiver to check (to see if they are up-to-date or not) remaining
    out of the 396 total files in the file-list.

    In an incremental recursion scan, rsync won't know the total number of
    files in the file-list until it reaches the ends of the scan, but since it
    starts to transfer files during the scan, it will display a line with the
    text "ir-chk" (for incremental recursion check) instead of "to-chk" until
    the point that it knows the full size of the list, at which point it will
    switch to using "to-chk".  Thus, seeing "ir-chk" lets you know that the
    total count of files in the file list is still going to increase (and each
    time it does, the count of files left to check will increase by the number
    of the files added to the list).

0.  `-P`

    The `-P` option is equivalent to "[`--partial`](#opt)
    [`--progress`](#opt)".  Its purpose is to make it much easier to specify
    these two options for a long transfer that may be interrupted.

    There is also a [`--info=progress2`](#opt) option that outputs statistics
    based on the whole transfer, rather than individual files.  Use this flag
    without outputting a filename (e.g. avoid `-v` or specify
    [`--info=name0`](#opt)) if you want to see how the transfer is doing
    without scrolling the screen with a lot of names. (You don't need to
    specify the [`--progress`](#opt) option in order to use
    [`--info=progress2`](#opt).)

    Finally, you can get an instant progress report by sending rsync a signal
    of either SIGINFO or SIGVTALRM.  On BSD systems, a SIGINFO is generated by
    typing a Ctrl+T (Linux doesn't currently support a SIGINFO signal).  When
    the client-side process receives one of those signals, it sets a flag to
    output a single progress report which is output when the current file
    transfer finishes (so it may take a little time if a big file is being
    handled when the signal arrives).  A filename is output (if needed)
    followed by the [`--info=progress2`](#opt) format of progress info.  If you
    don't know which of the 3 rsync processes is the client process, it's OK to
    signal all of them (since the non-client processes ignore the signal).

    CAUTION: sending SIGVTALRM to an older rsync (pre-3.2.0) will kill it.

0.  `--password-file=FILE`

    This option allows you to provide a password for accessing an rsync daemon
    via a file or via standard input if **FILE** is `-`.  The file should
    contain just the password on the first line (all other lines are ignored).
    Rsync will exit with an error if **FILE** is world readable or if a
    root-run rsync command finds a non-root-owned file.

    This option does not supply a password to a remote shell transport such as
    ssh; to learn how to do that, consult the remote shell's documentation.
    When accessing an rsync daemon using a remote shell as the transport, this
    option only comes into effect after the remote shell finishes its
    authentication (i.e. if you have also specified a password in the daemon's
    config file).

0.  `--early-input=FILE`

    This option allows rsync to send up to 5K of data to the "early exec"
    script on its stdin.  One possible use of this data is to give the script a
    secret that can be used to mount an encrypted filesystem (which you should
    unmount in the the "post-xfer exec" script).

    The daemon must be at least version 3.2.1.

0.  `--list-only`

    This option will cause the source files to be listed instead of
    transferred.  This option is inferred if there is a single source arg and
    no destination specified, so its main uses are:

    1. to turn a copy command that includes a destination arg into a
       file-listing command, or
    2. to be able to specify more than one source arg.  Note: be sure to
       include the destination.

    CAUTION: keep in mind that a source arg with a wild-card is expanded by the
    shell into multiple args, so it is never safe to try to specify a single
    wild-card arg to try to infer this option. A safe example is:

    >     rsync -av --list-only foo* dest/

    This option always uses an output format that looks similar to this:

    >     drwxrwxr-x          4,096 2022/09/30 12:53:11 support
    >     -rw-rw-r--             80 2005/01/11 10:37:37 support/Makefile

    The only option that affects this output style is (as of 3.1.0) the
    [`--human-readable`](#opt) (`-h`) option.  The default is to output sizes
    as byte counts with digit separators (in a 14-character-width column).
    Specifying at least one `-h` option makes the sizes output with unit
    suffixes.  If you want old-style bytecount sizes without digit separators
    (and an 11-character-width column) use `--no-h`.

    Compatibility note: when requesting a remote listing of files from an rsync
    that is version 2.6.3 or older, you may encounter an error if you ask for a
    non-recursive listing.  This is because a file listing implies the
    [`--dirs`](#opt) option w/o [`--recursive`](#opt), and older rsyncs don't
    have that option.  To avoid this problem, either specify the `--no-dirs`
    option (if you don't need to expand a directory's content), or turn on
    recursion and exclude the content of subdirectories: `-r --exclude='/*/*'`.

0.  `--bwlimit=RATE`

    This option allows you to specify the maximum transfer rate for the data
    sent over the socket, specified in units per second.  The RATE value can be
    suffixed with a string to indicate a size multiplier, and may be a
    fractional value (e.g. `--bwlimit=1.5m`).  If no suffix is specified, the
    value will be assumed to be in units of 1024 bytes (as if "K" or "KiB" had
    been appended).  See the [`--max-size`](#opt) option for a description of
    all the available suffixes.  A value of 0 specifies no limit.

    For backward-compatibility reasons, the rate limit will be rounded to the
    nearest KiB unit, so no rate smaller than 1024 bytes per second is
    possible.

    Rsync writes data over the socket in blocks, and this option both limits
    the size of the blocks that rsync writes, and tries to keep the average
    transfer rate at the requested limit.  Some burstiness may be seen where
    rsync writes out a block of data and then sleeps to bring the average rate
    into compliance.

    Due to the internal buffering of data, the [`--progress`](#opt) option may
    not be an accurate reflection on how fast the data is being sent.  This is
    because some files can show up as being rapidly sent when the data is
    quickly buffered, while other can show up as very slow when the flushing of
    the output buffer occurs.  This may be fixed in a future version.

    See also [the daemon version of the `--bwlimit` option](#dopt--bwlimit).

0.  `--stop-after=MINS`, (`--time-limit=MINS`)

    This option tells rsync to stop copying when the specified number of
    minutes has elapsed.

    For maximal flexibility, rsync does not communicate this option to the
    remote rsync since it is usually enough that one side of the connection
    quits as specified.  This allows the option's use even when only one side
    of the connection supports it.  You can tell the remote side about the time
    limit using [`--remote-option`](#opt) (`-M`), should the need arise.

    The `--time-limit` version of this option is deprecated.

0.  `--stop-at=y-m-dTh:m`

    This option tells rsync to stop copying when the specified point in time
    has been reached. The date & time can be fully specified in a numeric
    format of year-month-dayThour:minute (e.g. 2000-12-31T23:59) in the local
    timezone.  You may choose to separate the date numbers using slashes
    instead of dashes.

    The value can also be abbreviated in a variety of ways, such as specifying
    a 2-digit year and/or leaving off various values.  In all cases, the value
    will be taken to be the next possible point in time where the supplied
    information matches.  If the value specifies the current time or a past
    time, rsync exits with an error.

    For example, "1-30" specifies the next January 30th (at midnight local
    time), "14:00" specifies the next 2 P.M., "1" specifies the next 1st of the
    month at midnight, "31" specifies the next month where we can stop on its
    31st day, and ":59" specifies the next 59th minute after the hour.

    For maximal flexibility, rsync does not communicate this option to the
    remote rsync since it is usually enough that one side of the connection
    quits as specified.  This allows the option's use even when only one side
    of the connection supports it.  You can tell the remote side about the time
    limit using [`--remote-option`](#opt) (`-M`), should the need arise.  Do
    keep in mind that the remote host may have a different default timezone
    than your local host.

0.  `--fsync`

    Cause the receiving side to fsync each finished file.  This may slow down
    the transfer, but can help to provide peace of mind when updating critical
    files.

0.  `--write-batch=FILE`

    Record a file that can later be applied to another identical destination
    with [`--read-batch`](#opt).  See the "BATCH MODE" section for details, and
    also the [`--only-write-batch`](#opt) option.

    This option overrides the negotiated checksum & compress lists and always
    negotiates a choice based on old-school md5/md4/zlib choices.  If you want
    a more modern choice, use the [`--checksum-choice`](#opt) (`--cc`) and/or
    [`--compress-choice`](#opt) (`--zc`) options.

0.  `--only-write-batch=FILE`

    Works like [`--write-batch`](#opt), except that no updates are made on the
    destination system when creating the batch.  This lets you transport the
    changes to the destination system via some other means and then apply the
    changes via [`--read-batch`](#opt).

    Note that you can feel free to write the batch directly to some portable
    media: if this media fills to capacity before the end of the transfer, you
    can just apply that partial transfer to the destination and repeat the
    whole process to get the rest of the changes (as long as you don't mind a
    partially updated destination system while the multi-update cycle is
    happening).

    Also note that you only save bandwidth when pushing changes to a remote
    system because this allows the batched data to be diverted from the sender
    into the batch file without having to flow over the wire to the receiver
    (when pulling, the sender is remote, and thus can't write the batch).

0.  `--read-batch=FILE`

    Apply all of the changes stored in FILE, a file previously generated by
    [`--write-batch`](#opt).  If _FILE_ is `-`, the batch data will be read
    from standard input. See the "BATCH MODE" section for details.

0.  `--protocol=NUM`

    Force an older protocol version to be used.  This is useful for creating a
    batch file that is compatible with an older version of rsync.  For
    instance, if rsync 2.6.4 is being used with the [`--write-batch`](#opt)
    option, but rsync 2.6.3 is what will be used to run the
    [`--read-batch`](#opt) option, you should use "--protocol=28" when creating
    the batch file to force the older protocol version to be used in the batch
    file (assuming you can't upgrade the rsync on the reading system).

0.  `--iconv=CONVERT_SPEC`

    Rsync can convert filenames between character sets using this option.
    Using a CONVERT_SPEC of "." tells rsync to look up the default
    character-set via the locale setting.  Alternately, you can fully specify
    what conversion to do by giving a local and a remote charset separated by a
    comma in the order `--iconv=LOCAL,REMOTE`, e.g. `--iconv=utf8,iso88591`.
    This order ensures that the option will stay the same whether you're
    pushing or pulling files.  Finally, you can specify either `--no-iconv` or
    a CONVERT_SPEC of "-" to turn off any conversion.  The default setting of
    this option is site-specific, and can also be affected via the
    [`RSYNC_ICONV`](#) environment variable.

    For a list of what charset names your local iconv library supports, you can
    run "`iconv --list`".

    If you specify the [`--secluded-args`](#opt) (`-s`) option, rsync will
    translate the filenames you specify on the command-line that are being sent
    to the remote host.  See also the [`--files-from`](#opt) option.

    Note that rsync does not do any conversion of names in filter files
    (including include/exclude files).  It is up to you to ensure that you're
    specifying matching rules that can match on both sides of the transfer.
    For instance, you can specify extra include/exclude rules if there are
    filename differences on the two sides that need to be accounted for.

    When you pass an `--iconv` option to an rsync daemon that allows it, the
    daemon uses the charset specified in its "charset" configuration parameter
    regardless of the remote charset you actually pass.  Thus, you may feel
    free to specify just the local charset for a daemon transfer (e.g.
    `--iconv=utf8`).

0.  `--ipv4`, `-4` or `--ipv6`, `-6`

    Tells rsync to prefer IPv4/IPv6 when creating sockets or running ssh.  This
    affects sockets that rsync has direct control over, such as the outgoing
    socket when directly contacting an rsync daemon, as well as the forwarding
    of the `-4` or `-6` option to ssh when rsync can deduce that ssh is being
    used as the remote shell.  For other remote shells you'll need to specify
    the "`--rsh SHELL -4`" option directly (or whatever IPv4/IPv6 hint options
    it uses).

    See also [the daemon version of these options](#dopt--ipv4).

    If rsync was compiled without support for IPv6, the `--ipv6` option will
    have no effect.  The `rsync --version` output will contain "`no IPv6`" if
    is the case.

0.  `--checksum-seed=NUM`

    Set the checksum seed to the integer NUM.  This 4 byte checksum seed is
    included in each block and MD4 file checksum calculation (the more modern
    MD5 file checksums don't use a seed).  By default the checksum seed is
    generated by the server and defaults to the current **time**().  This
    option is used to set a specific checksum seed, which is useful for
    applications that want repeatable block checksums, or in the case where the
    user wants a more random checksum seed.  Setting NUM to 0 causes rsync to
    use the default of **time**() for checksum seed.

## DAEMON OPTIONS

The options allowed when starting an rsync daemon are as follows:

0.  `--daemon`

    This tells rsync that it is to run as a daemon.  The daemon you start
    running may be accessed using an rsync client using the `host::module` or
    `rsync://host/module/` syntax.

    If standard input is a socket then rsync will assume that it is being run
    via inetd, otherwise it will detach from the current terminal and become a
    background daemon.  The daemon will read the config file (rsyncd.conf) on
    each connect made by a client and respond to requests accordingly.

    See the [**rsyncd.conf**(5)](rsyncd.conf.5) manpage for more details.

0.  `--address=ADDRESS`

    By default rsync will bind to the wildcard address when run as a daemon
    with the `--daemon` option.  The `--address` option allows you to specify a
    specific IP address (or hostname) to bind to.  This makes virtual hosting
    possible in conjunction with the `--config` option.

    See also the [address](rsyncd.conf.5#address) global option in the
    rsyncd.conf manpage and the [client version of the `--address`
    option](#opt--address).

0.  `--bwlimit=RATE`

    This option allows you to specify the maximum transfer rate for the data
    the daemon sends over the socket.  The client can still specify a smaller
    `--bwlimit` value, but no larger value will be allowed.

    See the [client version of the `--bwlimit` option](#opt--bwlimit) for some
    extra details.

0.  `--config=FILE`

    This specifies an alternate config file than the default.  This is only
    relevant when [`--daemon`](#dopt) is specified.  The default is
    /etc/rsyncd.conf unless the daemon is running over a remote shell program
    and the remote user is not the super-user; in that case the default is
    rsyncd.conf in the current directory (typically $HOME).

0.  `--dparam=OVERRIDE`, `-M`

    This option can be used to set a daemon-config parameter when starting up
    rsync in daemon mode.  It is equivalent to adding the parameter at the end
    of the global settings prior to the first module's definition.  The
    parameter names can be specified without spaces, if you so desire.  For
    instance:

    >     rsync --daemon -M pidfile=/path/rsync.pid

0.  `--no-detach`

    When running as a daemon, this option instructs rsync to not detach itself
    and become a background process.  This option is required when running as a
    service on Cygwin, and may also be useful when rsync is supervised by a
    program such as `daemontools` or AIX's `System Resource Controller`.
    `--no-detach` is also recommended when rsync is run under a debugger.  This
    option has no effect if rsync is run from inetd or sshd.

0.  `--port=PORT`

    This specifies an alternate TCP port number for the daemon to listen on
    rather than the default of 873.

    See also [the client version of the `--port` option](#opt--port) and the
    [port](rsyncd.conf.5#port) global setting in the rsyncd.conf manpage.

0.  `--log-file=FILE`

    This option tells the rsync daemon to use the given log-file name instead
    of using the "`log file`" setting in the config file.

    See also [the client version of the `--log-file` option](#opt--log-file).

0.  `--log-file-format=FORMAT`

    This option tells the rsync daemon to use the given FORMAT string instead
    of using the "`log format`" setting in the config file.  It also enables
    "`transfer logging`" unless the string is empty, in which case transfer
    logging is turned off.

    See also [the client version of the `--log-file-format`
    option](#opt--log-file-format).

0.  `--sockopts`

    This overrides the [`socket options`](rsyncd.conf.5#socket_options)
    setting in the rsyncd.conf file and has the same syntax.

    See also [the client version of the `--sockopts` option](#opt--sockopts).

0.  `--verbose`, `-v`

    This option increases the amount of information the daemon logs during its
    startup phase.  After the client connects, the daemon's verbosity level
    will be controlled by the options that the client used and the
    "`max verbosity`" setting in the module's config section.

    See also [the client version of the `--verbose` option](#opt--verbose).

0.  `--ipv4`, `-4` or `--ipv6`, `-6`

    Tells rsync to prefer IPv4/IPv6 when creating the incoming sockets that the
    rsync daemon will use to listen for connections.  One of these options may
    be required in older versions of Linux to work around an IPv6 bug in the
    kernel (if you see an "address already in use" error when nothing else is
    using the port, try specifying `--ipv6` or `--ipv4` when starting the
    daemon).

    See also [the client version of these options](#opt--ipv4).

    If rsync was compiled without support for IPv6, the `--ipv6` option will
    have no effect.  The `rsync --version` output will contain "`no IPv6`" if
    is the case.

0.  `--help`, `-h`

    When specified after `--daemon`, print a short help page describing the
    options available for starting an rsync daemon.

## FILTER RULES

The filter rules allow for custom control of several aspects of how files are
handled:

- Control which files the sending side puts into the file list that describes
  the transfer hierarchy
- Control which files the receiving side protects from deletion when the file
  is not in the sender's file list
- Control which extended attribute names are skipped when copying xattrs

The rules are either directly specified via option arguments or they can be
read in from one or more files.  The filter-rule files can even be a part of
the hierarchy of files being copied, affecting different parts of the tree in
different ways.

### SIMPLE INCLUDE/EXCLUDE RULES

We will first cover the basics of how include & exclude rules affect what files
are transferred, ignoring any deletion side-effects.  Filter rules mainly
affect the contents of directories that rsync is "recursing" into, but they can
also affect a top-level item in the transfer that was specified as a argument.

The default for any unmatched file/dir is for it to be included in the
transfer, which puts the file/dir into the sender's file list.  The use of an
exclude rule causes one or more matching files/dirs to be left out of the
sender's file list.  An include rule can be used to limit the effect of an
exclude rule that is matching too many files.

The order of the rules is important because the first rule that matches is the
one that takes effect.  Thus, if an early rule excludes a file, no include rule
that comes after it can have any effect. This means that you must place any
include overrides somewhere prior to the exclude that it is intended to limit.

When a directory is excluded, all its contents and sub-contents are also
excluded.  The sender doesn't scan through any of it at all, which can save a
lot of time when skipping large unneeded sub-trees.

It is also important to understand that the include/exclude rules are applied
to every file and directory that the sender is recursing into. Thus, if you
want a particular deep file to be included, you have to make sure that none of
the directories that must be traversed on the way down to that file are
excluded or else the file will never be discovered to be included. As an
example, if the directory "`a/path`" was given as a transfer argument and you
want to ensure that the file "`a/path/down/deep/wanted.txt`" is a part of the
transfer, then the sender must not exclude the directories "`a/path`",
"`a/path/down`", or "`a/path/down/deep`" as it makes it way scanning through
the file tree.

When you are working on the rules, it can be helpful to ask rsync to tell you
what is being excluded/included and why.  Specifying `--debug=FILTER` or (when
pulling files) `-M--debug=FILTER` turns on level 1 of the FILTER debug
information that will output a message any time that a file or directory is
included or excluded and which rule it matched.  Beginning in 3.2.4 it will
also warn if a filter rule has trailing whitespace, since an exclude of "foo "
(with a trailing space) will not exclude a file named "foo".

Exclude and include rules can specify wildcard [PATTERN MATCHING RULES](#)
(similar to shell wildcards) that allow you to match things like a file suffix
or a portion of a filename.

A rule can be limited to only affecting a directory by putting a trailing slash
onto the filename.

### SIMPLE INCLUDE/EXCLUDE EXAMPLE

With the following file tree created on the sending side:

>     mkdir x/
>     touch x/file.txt
>     mkdir x/y/
>     touch x/y/file.txt
>     touch x/y/zzz.txt
>     mkdir x/z/
>     touch x/z/file.txt

Then the following rsync command will transfer the file "`x/y/file.txt`" and
the directories needed to hold it, resulting in the path "`/tmp/x/y/file.txt`"
existing on the remote host:

>     rsync -ai -f'+ x/' -f'+ x/y/' -f'+ x/y/file.txt' -f'- *' x host:/tmp/

Aside: this copy could also have been accomplished using the [`-R`](#opt)
option (though the 2 commands behave differently if deletions are enabled):

>     rsync -aiR x/y/file.txt host:/tmp/

The following command does not need an include of the "x" directory because it
is not a part of the transfer (note the traililng slash).  Running this command
would copy just "`/tmp/x/file.txt`" because the "y" and "z" dirs get excluded:

>     rsync -ai -f'+ file.txt' -f'- *' x/ host:/tmp/x/

This command would omit the zzz.txt file while copying "x" and everything else
it contains:

>     rsync -ai -f'- zzz.txt' x host:/tmp/

### FILTER RULES WHEN DELETING

By default the include & exclude filter rules affect both the sender
(as it creates its file list)
and the receiver (as it creates its file lists for calculating deletions).  If
no delete option is in effect, the receiver skips creating the delete-related
file lists.  This two-sided default can be manually overridden so that you are
only specifying sender rules or receiver rules, as described in the [FILTER
RULES IN DEPTH](#) section.

When deleting, an exclude protects a file from being removed on the receiving
side while an include overrides that protection (putting the file at risk of
deletion). The default is for a file to be at risk -- its safety depends on it
matching a corresponding file from the sender.

An example of the two-sided exclude effect can be illustrated by the copying of
a C development directory between 2 systems.  When doing a touch-up copy, you
might want to skip copying the built executable and the `.o` files (sender
hide) so that the receiving side can build their own and not lose any object
files that are already correct (receiver protect).  For instance:

>     rsync -ai --del -f'- *.o' -f'- cmd' src host:/dest/

Note that using `-f'-p *.o'` is even better than `-f'- *.o'` if there is a
chance that the directory structure may have changed.  The "p" modifier is
discussed in [FILTER RULE MODIFIERS](#).

One final note, if your shell doesn't mind unexpanded wildcards, you could
simplify the typing of the filter options by using an underscore in place of
the space and leaving off the quotes.  For instance, `-f -_*.o -f -_cmd` (and
similar) could be used instead of the filter options above.

### FILTER RULES IN DEPTH

Rsync supports old-style include/exclude rules and new-style filter rules.  The
older rules are specified using [`--include`](#opt) and [`--exclude`](#opt) as
well as the [`--include-from`](#opt) and [`--exclude-from`](#opt). These are
limited in behavior but they don't require a "-" or "+" prefix.  An old-style
exclude rule is turned into a "`- name`" filter rule (with no modifiers) and an
old-style include rule is turned into a "`+ name`" filter rule (with no
modifiers).

Rsync builds an ordered list of filter rules as specified on the command-line
and/or read-in from files.  New style filter rules have the following syntax:

>     RULE [PATTERN_OR_FILENAME]
>     RULE,MODIFIERS [PATTERN_OR_FILENAME]

You have your choice of using either short or long RULE names, as described
below.  If you use a short-named rule, the ',' separating the RULE from the
MODIFIERS is optional.  The PATTERN or FILENAME that follows (when present)
must come after either a single space or an underscore (\_). Any additional
spaces and/or underscores are considered to be a part of the pattern name.
Here are the available rule prefixes:

0.  `exclude, '-'` specifies an exclude pattern that (by default) is both a
    `hide` and a `protect`.
0.  `include, '+'` specifies an include pattern that (by default) is both a
    `show` and a `risk`.
0.  `merge, '.'` specifies a merge-file on the client side to read for more
    rules.
0.  `dir-merge, ':'` specifies a per-directory merge-file.  Using this kind of
    filter rule requires that you trust the sending side's filter checking, so
    it has the side-effect mentioned under the [`--trust-sender`](#opt) option.
0.  `hide, 'H'` specifies a pattern for hiding files from the transfer.
    Equivalent to a sender-only exclude, so `-f'H foo'` could also be specified
    as `-f'-s foo'`.
0.  `show, 'S'` files that match the pattern are not hidden. Equivalent to a
    sender-only include, so `-f'S foo'` could also be specified as `-f'+s
    foo'`.
0.  `protect, 'P'` specifies a pattern for protecting files from deletion.
    Equivalent to a receiver-only exclude, so `-f'P foo'` could also be
    specified as `-f'-r foo'`.
0.  `risk, 'R'` files that match the pattern are not protected. Equivalent to a
    receiver-only include, so `-f'R foo'` could also be specified as `-f'+r
    foo'`.
0.  `clear, '!'` clears the current include/exclude list (takes no arg)

When rules are being read from a file (using merge or dir-merge), empty lines
are ignored, as are whole-line comments that start with a '`#`' (filename rules
that contain a hash character are unaffected).

Note also that the [`--filter`](#opt), [`--include`](#opt), and
[`--exclude`](#opt) options take one rule/pattern each.  To add multiple ones,
you can repeat the options on the command-line, use the merge-file syntax of
the [`--filter`](#opt) option, or the [`--include-from`](#opt) /
[`--exclude-from`](#opt) options.

### PATTERN MATCHING RULES

Most of the rules mentioned above take an argument that specifies what the rule
should match.  If rsync is recursing through a directory hierarchy, keep in
mind that each pattern is matched against the name of every directory in the
descent path as rsync finds the filenames to send.

The matching rules for the pattern argument take several forms:

- If a pattern contains a `/` (not counting a trailing slash) or a "`**`"
  (which can match a slash), then the pattern is matched against the full
  pathname, including any leading directories within the transfer.  If the
  pattern doesn't contain a (non-trailing) `/` or a "`**`", then it is matched
  only against the final component of the filename or pathname. For example,
  `foo` means that the final path component must be "foo" while `foo/bar` would
  match the last 2 elements of the path (as long as both elements are within
  the transfer).
- A pattern that ends with a `/` only matches a directory, not a regular file,
  symlink, or device.
- A pattern that starts with a `/` is anchored to the start of the transfer
  path instead of the end.  For example, `/foo/**` or `/foo/bar/**` match only
  leading elements in the path.  If the rule is read from a per-directory
  filter file, the transfer path being matched will begin at the level of the
  filter file instead of the top of the transfer.  See the section on
  [ANCHORING INCLUDE/EXCLUDE PATTERNS](#) for a full discussion of how to
  specify a pattern that matches at the root of the transfer.

Rsync chooses between doing a simple string match and wildcard matching by
checking if the pattern contains one of these three wildcard characters: '`*`',
'`?`', and '`[`' :

- a '`?`' matches any single character except a slash (`/`).
- a '`*`' matches zero or more non-slash characters.
- a '`**`' matches zero or more characters, including slashes.
- a '`[`' introduces a character class, such as `[a-z]` or `[[:alpha:]]`, that
  must match one character.
- a trailing `***` in the pattern is a shorthand that allows you to match a
  directory and all its contents using a single rule.  For example, specifying
  "`dir_name/***`" will match both the "dir_name" directory (as if "`dir_name/`"
  had been specified) and everything in the directory (as if "`dir_name/**`"
  had been specified).
- a backslash can be used to escape a wildcard character, but it is only
  interpreted as an escape character if at least one wildcard character is
  present in the match pattern. For instance, the pattern "`foo\bar`" matches
  that single backslash literally, while the pattern "`foo\bar*`" would need to
  be changed to "`foo\\bar*`" to avoid the "`\b`" becoming just "b".

Here are some examples of exclude/include matching:

- Option `-f'- *.o'` would exclude all filenames ending with `.o`
- Option `-f'- /foo'` would exclude a file (or directory) named foo in the
  transfer-root directory
- Option `-f'- foo/'` would exclude any directory named foo
- Option `-f'- foo/*/bar'` would exclude any file/dir named bar which is at two
  levels below a directory named foo (if foo is in the transfer)
- Option `-f'- /foo/**/bar'` would exclude any file/dir named bar that was two
  or more levels below a top-level directory named foo (note that /foo/bar is
  **not** excluded by this)
- Options `-f'+ */' -f'+ *.c' -f'- *'` would include all directories and .c
  source files but nothing else
- Options `-f'+ foo/' -f'+ foo/bar.c' -f'- *'` would include only the foo
  directory and foo/bar.c (the foo directory must be explicitly included or it
  would be excluded by the "`- *`")

### FILTER RULE MODIFIERS

The following modifiers are accepted after an include (+) or exclude (-) rule:

- A `/` specifies that the include/exclude rule should be matched against the
  absolute pathname of the current item.  For example, `-f'-/ /etc/passwd'`
  would exclude the passwd file any time the transfer was sending files from
  the "/etc" directory, and "-/ subdir/foo" would always exclude "foo" when it
  is in a dir named "subdir", even if "foo" is at the root of the current
  transfer.
- A `!` specifies that the include/exclude should take effect if the pattern
  fails to match.  For instance, `-f'-! */'` would exclude all non-directories.
- A `C` is used to indicate that all the global CVS-exclude rules should be
  inserted as excludes in place of the "-C".  No arg should follow.
- An `s` is used to indicate that the rule applies to the sending side.  When a
  rule affects the sending side, it affects what files are put into the
  sender's file list.  The default is for a rule to affect both sides unless
  [`--delete-excluded`](#opt) was specified, in which case default rules become
  sender-side only.  See also the hide (H) and show (S) rules, which are an
  alternate way to specify sending-side includes/excludes.
- An `r` is used to indicate that the rule applies to the receiving side.  When
  a rule affects the receiving side, it prevents files from being deleted.  See
  the `s` modifier for more info.  See also the protect (P) and risk (R) rules,
  which are an alternate way to specify receiver-side includes/excludes.
- A `p` indicates that a rule is perishable, meaning that it is ignored in
  directories that are being deleted.  For instance, the
  [`--cvs-exclude`](#opt) (`-C`) option's default rules that exclude things
  like "CVS" and "`*.o`" are marked as perishable, and will not prevent a
  directory that was removed on the source from being deleted on the
  destination.
- An `x` indicates that a rule affects xattr names in xattr copy/delete
  operations (and is thus ignored when matching file/dir names).  If no
  xattr-matching rules are specified, a default xattr filtering rule is used
  (see the [`--xattrs`](#opt) option).

### MERGE-FILE FILTER RULES

You can merge whole files into your filter rules by specifying either a merge
(.) or a dir-merge (:) filter rule (as introduced in the [FILTER RULES](#)
section above).

There are two kinds of merged files -- single-instance ('.') and per-directory
(':').  A single-instance merge file is read one time, and its rules are
incorporated into the filter list in the place of the "." rule.  For
per-directory merge files, rsync will scan every directory that it traverses
for the named file, merging its contents when the file exists into the current
list of inherited rules.  These per-directory rule files must be created on the
sending side because it is the sending side that is being scanned for the
available files to transfer.  These rule files may also need to be transferred
to the receiving side if you want them to affect what files don't get deleted
(see [PER-DIRECTORY RULES AND DELETE](#) below).

Some examples:

>     merge /etc/rsync/default.rules
>     . /etc/rsync/default.rules
>     dir-merge .per-dir-filter
>     dir-merge,n- .non-inherited-per-dir-excludes
>     :n- .non-inherited-per-dir-excludes

The following modifiers are accepted after a merge or dir-merge rule:

- A `-` specifies that the file should consist of only exclude patterns, with
  no other rule-parsing except for in-file comments.
- A `+` specifies that the file should consist of only include patterns, with
  no other rule-parsing except for in-file comments.
- A `C` is a way to specify that the file should be read in a CVS-compatible
  manner.  This turns on 'n', 'w', and '-', but also allows the list-clearing
  token (!) to be specified.  If no filename is provided, ".cvsignore" is
  assumed.
- A `e` will exclude the merge-file name from the transfer; e.g.  "dir-merge,e
  .rules" is like "dir-merge .rules" and "- .rules".
- An `n` specifies that the rules are not inherited by subdirectories.
- A `w` specifies that the rules are word-split on whitespace instead of the
  normal line-splitting.  This also turns off comments.  Note: the space that
  separates the prefix from the rule is treated specially, so "- foo + bar" is
  parsed as two rules (assuming that prefix-parsing wasn't also disabled).
- You may also specify any of the modifiers for the "+" or "-" rules (above) in
  order to have the rules that are read in from the file default to having that
  modifier set (except for the `!` modifier, which would not be useful).  For
  instance, "merge,-/ .excl" would treat the contents of .excl as absolute-path
  excludes, while "dir-merge,s .filt" and ":sC" would each make all their
  per-directory rules apply only on the sending side.  If the merge rule
  specifies sides to affect (via the `s` or `r` modifier or both), then the
  rules in the file must not specify sides (via a modifier or a rule prefix
  such as `hide`).

Per-directory rules are inherited in all subdirectories of the directory where
the merge-file was found unless the 'n' modifier was used.  Each subdirectory's
rules are prefixed to the inherited per-directory rules from its parents, which
gives the newest rules a higher priority than the inherited rules.  The entire
set of dir-merge rules are grouped together in the spot where the merge-file
was specified, so it is possible to override dir-merge rules via a rule that
got specified earlier in the list of global rules.  When the list-clearing rule
("!") is read from a per-directory file, it only clears the inherited rules for
the current merge file.

Another way to prevent a single rule from a dir-merge file from being inherited
is to anchor it with a leading slash.  Anchored rules in a per-directory
merge-file are relative to the merge-file's directory, so a pattern "/foo"
would only match the file "foo" in the directory where the dir-merge filter
file was found.

Here's an example filter file which you'd specify via `--filter=". file":`

>     merge /home/user/.global-filter
>     - *.gz
>     dir-merge .rules
>     + *.[ch]
>     - *.o
>     - foo*

This will merge the contents of the /home/user/.global-filter file at the start
of the list and also turns the ".rules" filename into a per-directory filter
file.  All rules read in prior to the start of the directory scan follow the
global anchoring rules (i.e. a leading slash matches at the root of the
transfer).

If a per-directory merge-file is specified with a path that is a parent
directory of the first transfer directory, rsync will scan all the parent dirs
from that starting point to the transfer directory for the indicated
per-directory file.  For instance, here is a common filter (see [`-F`](#opt)):

>     --filter=': /.rsync-filter'

That rule tells rsync to scan for the file .rsync-filter in all directories
from the root down through the parent directory of the transfer prior to the
start of the normal directory scan of the file in the directories that are sent
as a part of the transfer. (Note: for an rsync daemon, the root is always the
same as the module's "path".)

Some examples of this pre-scanning for per-directory files:

>     rsync -avF /src/path/ /dest/dir
>     rsync -av --filter=': ../../.rsync-filter' /src/path/ /dest/dir
>     rsync -av --filter=': .rsync-filter' /src/path/ /dest/dir

The first two commands above will look for ".rsync-filter" in "/" and "/src"
before the normal scan begins looking for the file in "/src/path" and its
subdirectories.  The last command avoids the parent-dir scan and only looks for
the ".rsync-filter" files in each directory that is a part of the transfer.

If you want to include the contents of a ".cvsignore" in your patterns, you
should use the rule ":C", which creates a dir-merge of the .cvsignore file, but
parsed in a CVS-compatible manner.  You can use this to affect where the
[`--cvs-exclude`](#opt) (`-C`) option's inclusion of the per-directory
.cvsignore file gets placed into your rules by putting the ":C" wherever you
like in your filter rules.  Without this, rsync would add the dir-merge rule
for the .cvsignore file at the end of all your other rules (giving it a lower
priority than your command-line rules).  For example:

> ```
> cat <<EOT | rsync -avC --filter='. -' a/ b
> + foo.o
> :C
> - *.old
> EOT
> rsync -avC --include=foo.o -f :C --exclude='*.old' a/ b
> ```

Both of the above rsync commands are identical.  Each one will merge all the
per-directory .cvsignore rules in the middle of the list rather than at the
end.  This allows their dir-specific rules to supersede the rules that follow
the :C instead of being subservient to all your rules.  To affect the other CVS
exclude rules (i.e. the default list of exclusions, the contents of
$HOME/.cvsignore, and the value of $CVSIGNORE) you should omit the `-C`
command-line option and instead insert a "-C" rule into your filter rules; e.g.
"`--filter=-C`".

### LIST-CLEARING FILTER RULE

You can clear the current include/exclude list by using the "!" filter rule (as
introduced in the [FILTER RULES](#) section above).  The "current" list is either
the global list of rules (if the rule is encountered while parsing the filter
options) or a set of per-directory rules (which are inherited in their own
sub-list, so a subdirectory can use this to clear out the parent's rules).

### ANCHORING INCLUDE/EXCLUDE PATTERNS

As mentioned earlier, global include/exclude patterns are anchored at the "root
of the transfer" (as opposed to per-directory patterns, which are anchored at
the merge-file's directory).  If you think of the transfer as a subtree of
names that are being sent from sender to receiver, the transfer-root is where
the tree starts to be duplicated in the destination directory.  This root
governs where patterns that start with a / match.

Because the matching is relative to the transfer-root, changing the trailing
slash on a source path or changing your use of the [`--relative`](#opt) option
affects the path you need to use in your matching (in addition to changing how
much of the file tree is duplicated on the destination host).  The following
examples demonstrate this.

Let's say that we want to match two source files, one with an absolute
path of "/home/me/foo/bar", and one with a path of "/home/you/bar/baz".
Here is how the various command choices differ for a 2-source transfer:

> ```
> Example cmd: rsync -a /home/me /home/you /dest
> +/- pattern: /me/foo/bar
> +/- pattern: /you/bar/baz
> Target file: /dest/me/foo/bar
> Target file: /dest/you/bar/baz
> ```

> ```
> Example cmd: rsync -a /home/me/ /home/you/ /dest
> +/- pattern: /foo/bar               (note missing "me")
> +/- pattern: /bar/baz               (note missing "you")
> Target file: /dest/foo/bar
> Target file: /dest/bar/baz
> ```

> ```
> Example cmd: rsync -a --relative /home/me/ /home/you /dest
> +/- pattern: /home/me/foo/bar       (note full path)
> +/- pattern: /home/you/bar/baz      (ditto)
> Target file: /dest/home/me/foo/bar
> Target file: /dest/home/you/bar/baz
> ```

> ```
> Example cmd: cd /home; rsync -a --relative me/foo you/ /dest
> +/- pattern: /me/foo/bar      (starts at specified path)
> +/- pattern: /you/bar/baz     (ditto)
> Target file: /dest/me/foo/bar
> Target file: /dest/you/bar/baz
> ```

The easiest way to see what name you should filter is to just look at the
output when using [`--verbose`](#opt) and put a / in front of the name (use the
`--dry-run` option if you're not yet ready to copy any files).

### PER-DIRECTORY RULES AND DELETE

Without a delete option, per-directory rules are only relevant on the sending
side, so you can feel free to exclude the merge files themselves without
affecting the transfer.  To make this easy, the 'e' modifier adds this exclude
for you, as seen in these two equivalent commands:

>     rsync -av --filter=': .excl' --exclude=.excl host:src/dir /dest
>     rsync -av --filter=':e .excl' host:src/dir /dest

However, if you want to do a delete on the receiving side AND you want some
files to be excluded from being deleted, you'll need to be sure that the
receiving side knows what files to exclude.  The easiest way is to include the
per-directory merge files in the transfer and use [`--delete-after`](#opt),
because this ensures that the receiving side gets all the same exclude rules as
the sending side before it tries to delete anything:

>     rsync -avF --delete-after host:src/dir /dest

However, if the merge files are not a part of the transfer, you'll need to
either specify some global exclude rules (i.e. specified on the command line),
or you'll need to maintain your own per-directory merge files on the receiving
side.  An example of the first is this (assume that the remote .rules files
exclude themselves):

>     rsync -av --filter=': .rules' --filter='. /my/extra.rules'
>        --delete host:src/dir /dest

In the above example the extra.rules file can affect both sides of the
transfer, but (on the sending side) the rules are subservient to the rules
merged from the .rules files because they were specified after the
per-directory merge rule.

In one final example, the remote side is excluding the .rsync-filter files from
the transfer, but we want to use our own .rsync-filter files to control what
gets deleted on the receiving side.  To do this we must specifically exclude
the per-directory merge files (so that they don't get deleted) and then put
rules into the local files to control what else should not get deleted.  Like
one of these commands:

> ```
> rsync -av --filter=':e /.rsync-filter' --delete \
>     host:src/dir /dest
> rsync -avFF --delete host:src/dir /dest
> ```

## TRANSFER RULES

In addition to the [FILTER RULES](#) that affect the recursive file scans that
generate the file list on the sending and (when deleting) receiving sides,
there are transfer rules. These rules affect which files the generator decides
need to be transferred without the side effects of an exclude filter rule.
Transfer rules affect only files and never directories.

Because a transfer rule does not affect what goes into the sender's (and
receiver's) file list, it cannot have any effect on which files get deleted on
the receiving side.  For example, if the file "foo" is present in the sender's
list but its size is such that it is omitted due to a transfer rule, the
receiving side does not request the file.  However, its presence in the file
list means that a delete pass will not remove a matching file named "foo" on
the receiving side.  On the other hand, a server-side exclude (hide) of the
file "foo" leaves the file out of the server's file list, and absent a
receiver-side exclude (protect) the receiver will remove a matching file named
"foo" if deletions are requested.

Given that the files are still in the sender's file list, the
[`--prune-empty-dirs`](#opt) option will not judge a directory as being empty
even if it contains only files that the transfer rules omitted.

Similarly, a transfer rule does not have any extra effect on which files are
deleted on the receiving side, so setting a maximum file size for the transfer
does not prevent big files from being deleted.

Examples of transfer rules include the default "quick check" algorithm (which
compares size & modify time), the [`--update`](#opt) option, the
[`--max-size`](#opt) option, the [`--ignore-non-existing`](#opt) option, and a
few others.

## BATCH MODE

Batch mode can be used to apply the same set of updates to many identical
systems.  Suppose one has a tree which is replicated on a number of hosts.  Now
suppose some changes have been made to this source tree and those changes need
to be propagated to the other hosts.  In order to do this using batch mode,
rsync is run with the write-batch option to apply the changes made to the
source tree to one of the destination trees.  The write-batch option causes the
rsync client to store in a "batch file" all the information needed to repeat
this operation against other, identical destination trees.

Generating the batch file once saves having to perform the file status,
checksum, and data block generation more than once when updating multiple
destination trees.  Multicast transport protocols can be used to transfer the
batch update files in parallel to many hosts at once, instead of sending the
same data to every host individually.

To apply the recorded changes to another destination tree, run rsync with the
read-batch option, specifying the name of the same batch file, and the
destination tree.  Rsync updates the destination tree using the information
stored in the batch file.

For your convenience, a script file is also created when the write-batch option
is used: it will be named the same as the batch file with ".sh" appended.  This
script file contains a command-line suitable for updating a destination tree
using the associated batch file.  It can be executed using a Bourne (or
Bourne-like) shell, optionally passing in an alternate destination tree
pathname which is then used instead of the original destination path.  This is
useful when the destination tree path on the current host differs from the one
used to create the batch file.

Examples:

>     $ rsync --write-batch=foo -a host:/source/dir/ /adest/dir/
>     $ scp foo* remote:
>     $ ssh remote ./foo.sh /bdest/dir/

>     $ rsync --write-batch=foo -a /source/dir/ /adest/dir/
>     $ ssh remote rsync --read-batch=- -a /bdest/dir/ <foo

In these examples, rsync is used to update /adest/dir/ from /source/dir/ and
the information to repeat this operation is stored in "foo" and "foo.sh".  The
host "remote" is then updated with the batched data going into the directory
/bdest/dir.  The differences between the two examples reveals some of the
flexibility you have in how you deal with batches:

- The first example shows that the initial copy doesn't have to be local -- you
  can push or pull data to/from a remote host using either the remote-shell
  syntax or rsync daemon syntax, as desired.
- The first example uses the created "foo.sh" file to get the right rsync
  options when running the read-batch command on the remote host.
- The second example reads the batch data via standard input so that the batch
  file doesn't need to be copied to the remote machine first.  This example
  avoids the foo.sh script because it needed to use a modified
  [`--read-batch`](#opt) option, but you could edit the script file if you
  wished to make use of it (just be sure that no other option is trying to use
  standard input, such as the [`--exclude-from=-`](#opt) option).

Caveats:

The read-batch option expects the destination tree that it is updating to be
identical to the destination tree that was used to create the batch update
fileset.  When a difference between the destination trees is encountered the
update might be discarded with a warning (if the file appears to be up-to-date
already) or the file-update may be attempted and then, if the file fails to
verify, the update discarded with an error.  This means that it should be safe
to re-run a read-batch operation if the command got interrupted.  If you wish
to force the batched-update to always be attempted regardless of the file's
size and date, use the [`-I`](#opt) option (when reading the batch).  If an
error occurs, the destination tree will probably be in a partially updated
state.  In that case, rsync can be used in its regular (non-batch) mode of
operation to fix up the destination tree.

The rsync version used on all destinations must be at least as new as the one
used to generate the batch file.  Rsync will die with an error if the protocol
version in the batch file is too new for the batch-reading rsync to handle.
See also the [`--protocol`](#opt) option for a way to have the creating rsync
generate a batch file that an older rsync can understand.  (Note that batch
files changed format in version 2.6.3, so mixing versions older than that with
newer versions will not work.)

When reading a batch file, rsync will force the value of certain options to
match the data in the batch file if you didn't set them to the same as the
batch-writing command.  Other options can (and should) be changed.  For
instance [`--write-batch`](#opt) changes to [`--read-batch`](#opt),
[`--files-from`](#opt) is dropped, and the [`--filter`](#opt) /
[`--include`](#opt) / [`--exclude`](#opt) options are not needed unless one of
the [`--delete`](#opt) options is specified.

The code that creates the BATCH.sh file transforms any filter/include/exclude
options into a single list that is appended as a "here" document to the shell
script file.  An advanced user can use this to modify the exclude list if a
change in what gets deleted by [`--delete`](#opt) is desired.  A normal user
can ignore this detail and just use the shell script as an easy way to run the
appropriate [`--read-batch`](#opt) command for the batched data.

The original batch mode in rsync was based on "rsync+", but the latest
version uses a new implementation.

## SYMBOLIC LINKS

Three basic behaviors are possible when rsync encounters a symbolic
link in the source directory.

By default, symbolic links are not transferred at all.  A message "skipping
non-regular" file is emitted for any symlinks that exist.

If [`--links`](#opt) is specified, then symlinks are added to the transfer
(instead of being noisily ignored), and the default handling is to recreate
them with the same target on the destination.  Note that [`--archive`](#opt)
implies [`--links`](#opt).

If [`--copy-links`](#opt) is specified, then symlinks are "collapsed" by
copying their referent, rather than the symlink.

Rsync can also distinguish "safe" and "unsafe" symbolic links.  An example
where this might be used is a web site mirror that wishes to ensure that the
rsync module that is copied does not include symbolic links to `/etc/passwd` in
the public section of the site.  Using [`--copy-unsafe-links`](#opt) will cause
any links to be copied as the file they point to on the destination.  Using
[`--safe-links`](#opt) will cause unsafe links to be omitted by the receiver.
(Note that you must specify or imply [`--links`](#opt) for
[`--safe-links`](#opt) to have any effect.)

Symbolic links are considered unsafe if they are absolute symlinks (start with
`/`), empty, or if they contain enough ".." components to ascend from the top
of the transfer.

Here's a summary of how the symlink options are interpreted.  The list is in
order of precedence, so if your combination of options isn't mentioned, use the
first line that is a complete subset of your options:

0.  `--copy-links` Turn all symlinks into normal files and directories
    (leaving no symlinks in the transfer for any other options to affect).
0.  `--copy-dirlinks` Turn just symlinks to directories into real
    directories, leaving all other symlinks to be handled as described below.
0.  `--links --copy-unsafe-links` Turn all unsafe symlinks
    into files and create all safe symlinks.
0.  `--copy-unsafe-links` Turn all unsafe symlinks into files, noisily
    skip all safe symlinks.
0.  `--links --safe-links` The receiver skips creating
    unsafe symlinks found in the transfer and creates the safe ones.
0.  `--links` Create all symlinks.

For the effect of [`--munge-links`](#opt), see the discussion in that option's
section.

Note that the [`--keep-dirlinks`](#opt) option does not effect symlinks in the
transfer but instead affects how rsync treats a symlink to a directory that
already exists on the receiving side.  See that option's section for a warning.

## DIAGNOSTICS

Rsync occasionally produces error messages that may seem a little cryptic.  The
one that seems to cause the most confusion is "protocol version mismatch -- is
your shell clean?".

This message is usually caused by your startup scripts or remote shell facility
producing unwanted garbage on the stream that rsync is using for its transport.
The way to diagnose this problem is to run your remote shell like this:

>     ssh remotehost /bin/true > out.dat

then look at out.dat.  If everything is working correctly then out.dat should
be a zero length file.  If you are getting the above error from rsync then you
will probably find that out.dat contains some text or data.  Look at the
contents and try to work out what is producing it.  The most common cause is
incorrectly configured shell startup scripts (such as .cshrc or .profile) that
contain output statements for non-interactive logins.

If you are having trouble debugging filter patterns, then try specifying the
`-vv` option.  At this level of verbosity rsync will show why each individual
file is included or excluded.

## EXIT VALUES

- **0** - Success
- **1** - Syntax or usage error
- **2** - Protocol incompatibility
- **3** - Errors selecting input/output files, dirs
- **4** - Requested action not supported. Either:
  - an attempt was made to manipulate 64-bit files on a platform that cannot support them
  - an option was specified that is supported by the client and not by the server
- **5** - Error starting client-server protocol
- **6** - Daemon unable to append to log-file
- **10** - Error in socket I/O
- **11** - Error in file I/O
- **12** - Error in rsync protocol data stream
- **13** - Errors with program diagnostics
- **14** - Error in IPC code
- **20** - Received SIGUSR1 or SIGINT
- **21** - Some error returned by **waitpid()**
- **22** - Error allocating core memory buffers
- **23** - Partial transfer due to error
- **24** - Partial transfer due to vanished source files
- **25** - The --max-delete limit stopped deletions
- **30** - Timeout in data send/receive
- **35** - Timeout waiting for daemon connection

## ENVIRONMENT VARIABLES

0.  `CVSIGNORE`

    The CVSIGNORE environment variable supplements any ignore patterns in
    .cvsignore files.  See the [`--cvs-exclude`](#opt) option for more details.

0.  `RSYNC_ICONV`

    Specify a default [`--iconv`](#opt) setting using this environment
    variable. First supported in 3.0.0.

0.  `RSYNC_OLD_ARGS`

    Specify a "1" if you want the [`--old-args`](#opt) option to be enabled by
    default, a "2" (or more) if you want it to be enabled in the
    repeated-option state, or a "0" to make sure that it is disabled by
    default. When this environment variable is set to a non-zero value, it
    supersedes the [`RSYNC_PROTECT_ARGS`](#) variable.

    This variable is ignored if [`--old-args`](#opt), `--no-old-args`, or
    [`--secluded-args`](#opt) is specified on the command line.

    First supported in 3.2.4.

0.  `RSYNC_PROTECT_ARGS`

    Specify a non-zero numeric value if you want the [`--secluded-args`](#opt)
    option to be enabled by default, or a zero value to make sure that it is
    disabled by default.

    This variable is ignored if [`--secluded-args`](#opt), `--no-secluded-args`,
    or [`--old-args`](#opt) is specified on the command line.

    First supported in 3.1.0.  Starting in 3.2.4, this variable is ignored if
    [`RSYNC_OLD_ARGS`](#) is set to a non-zero value.

0.  `RSYNC_RSH`

    This environment variable allows you to override the default shell used as
    the transport for rsync.  Command line options are permitted after the
    command name, just as in the [`--rsh`](#opt) (`-e`) option.

0.  `RSYNC_PROXY`

    This environment variable allows you to redirect your rsync
    client to use a web proxy when connecting to an rsync daemon.  You should
    set `RSYNC_PROXY` to a hostname:port pair.

0.  `RSYNC_PASSWORD`

    This environment variable allows you to set the password for an rsync
    **daemon** connection, which avoids the password prompt.  Note that this
    does **not** supply a password to a remote shell transport such as ssh
    (consult its documentation for how to do that).

0.  `USER` or `LOGNAME`

    The USER or LOGNAME environment variables are used to determine the default
    username sent to an rsync daemon.  If neither is set, the username defaults
    to "nobody".  If both are set, `USER` takes precedence.

0. `RSYNC_PARTIAL_DIR`

    This environment variable specifies the directory to use for a
    [`--partial`](#opt) transfer without implying that partial transfers be
    enabled.  See the [`--partial-dir`](#opt) option for full details.

0. `RSYNC_COMPRESS_LIST`

    This environment variable allows you to customize the negotiation of the
    compression algorithm by specifying an alternate order or a reduced list of
    names.  Use the command `rsync --version` to see the available compression
    names.  See the [`--compress`](#opt) option for full details.

0. `RSYNC_CHECKSUM_LIST`

    This environment variable allows you to customize the negotiation of the
    checksum algorithm by specifying an alternate order or a reduced list of
    names.  Use the command `rsync --version` to see the available checksum
    names.  See the [`--checksum-choice`](#opt) option for full details.

0. `RSYNC_MAX_ALLOC`

    This environment variable sets an allocation maximum as if you had used the
    [`--max-alloc`](#opt) option.

0. `RSYNC_PORT`

    This environment variable is not read by rsync, but is instead set in
    its sub-environment when rsync is running the remote shell in combination
    with a daemon connection.  This allows a script such as
    [`rsync-ssl`](rsync-ssl.1) to be able to know the port number that the user
    specified on the command line.

0.  `HOME`

    This environment variable is used to find the user's default .cvsignore
    file.

0. `RSYNC_CONNECT_PROG`

    This environment variable is mainly used in debug setups to set the program
    to use when making a daemon connection.  See [CONNECTING TO AN RSYNC
    DAEMON](#) for full details.

0. `RSYNC_SHELL`

    This environment variable is mainly used in debug setups to set the program
    to use to run the program specified by [`RSYNC_CONNECT_PROG`](#).  See
    [CONNECTING TO AN RSYNC DAEMON](#) for full details.

## FILES

/etc/rsyncd.conf or rsyncd.conf

## SEE ALSO

[**rsync-ssl**(1)](rsync-ssl.1), [**rsyncd.conf**(5)](rsyncd.conf.5), [**rrsync**(1)](rrsync.1)

## BUGS

- Times are transferred as \*nix time_t values.
- When transferring to FAT filesystems rsync may re-sync unmodified files.  See
  the comments on the [`--modify-window`](#opt) option.
- File permissions, devices, etc. are transferred as native numerical values.
- See also the comments on the [`--delete`](#opt) option.

Please report bugs! See the web site at <https://rsync.samba.org/>.

## VERSION

This manpage is current for version @VERSION@ of rsync.

## INTERNAL OPTIONS

The options `--server` and `--sender` are used internally by rsync, and should
never be typed by a user under normal circumstances.  Some awareness of these
options may be needed in certain scenarios, such as when setting up a login
that can only run an rsync command.  For instance, the support directory of the
rsync distribution has an example script named rrsync (for restricted rsync)
that can be used with a restricted ssh login.

## CREDITS

Rsync is distributed under the GNU General Public License.  See the file
[COPYING](COPYING) for details.

An rsync web site is available at <https://rsync.samba.org/>.  The site
includes an FAQ-O-Matic which may cover questions unanswered by this manual
page.

The rsync github project is <https://github.com/WayneD/rsync>.

We would be delighted to hear from you if you like this program.  Please
contact the mailing-list at <rsync@lists.samba.org>.

This program uses the excellent zlib compression library written by Jean-loup
Gailly and Mark Adler.

## THANKS

Special thanks go out to: John Van Essen, Matt McCutchen, Wesley W. Terpstra,
David Dykstra, Jos Backus, Sebastian Krahmer, Martin Pool, and our
gone-but-not-forgotten compadre, J.W. Schultz.

Thanks also to Richard Brent, Brendan Mackay, Bill Waite, Stephen Rothwell and
David Bell.  I've probably missed some people, my apologies if I have.

## AUTHOR

Rsync was originally written by Andrew Tridgell and Paul Mackerras.  Many
people have later contributed to it. It is currently maintained by Wayne
Davison.

Mailing lists for support and development are available at
<https://lists.samba.org/>.