Autogenerated manpages for v2.44.0-53-g0f9d4

[git-manpages.git] / man7 / gitglossary.7

'\" t
.\"     Title: gitglossary
.\"    Author: [FIXME: author] [see http://www.docbook.org/tdg5/en/html/author]
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 2024-02-27
.\"    Manual: Git Manual
.\"    Source: Git 2.44.0.53.g0f9d4d28b7
.\"  Language: English
.\"
.TH "GITGLOSSARY" "7" "2024\-02\-27" "Git 2\&.44\&.0\&.53\&.g0f9d4d2" "Git Manual"
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.SH "NAME"
gitglossary \- A Git Glossary
.SH "SYNOPSIS"
.sp
*
.SH "DESCRIPTION"
.PP
alternate object database
.RS 4
Via the alternates mechanism, a
repository
can inherit part of its
object database
from another object database, which is called an "alternate"\&.
.RE
.PP
bare repository
.RS 4
A bare repository is normally an appropriately named
directory
with a
\fB\&.git\fR
suffix that does not have a locally checked\-out copy of any of the files under revision control\&. That is, all of the Git administrative and control files that would normally be present in the hidden
\fB\&.git\fR
sub\-directory are directly present in the
\fBrepository\&.git\fR
directory instead, and no other files are present and checked out\&. Usually publishers of public repositories make bare repositories available\&.
.RE
.PP
blob object
.RS 4
Untyped
object, e\&.g\&. the contents of a file\&.
.RE
.PP
branch
.RS 4
A "branch" is a line of development\&. The most recent
commit
on a branch is referred to as the tip of that branch\&. The tip of the branch is
referenced
by a branch
head, which moves forward as additional development is done on the branch\&. A single Git
repository
can track an arbitrary number of branches, but your
working tree
is associated with just one of them (the "current" or "checked out" branch), and
HEAD
points to that branch\&.
.RE
.PP
cache
.RS 4
Obsolete for:
index\&.
.RE
.PP
chain
.RS 4
A list of objects, where each
object
in the list contains a reference to its successor (for example, the successor of a
commit
could be one of its
parents)\&.
.RE
.PP
changeset
.RS 4
BitKeeper/cvsps speak for "commit"\&. Since Git does not store changes, but states, it really does not make sense to use the term "changesets" with Git\&.
.RE
.PP
checkout
.RS 4
The action of updating all or part of the
working tree
with a
tree object
or
blob
from the
object database, and updating the
index
and
HEAD
if the whole working tree has been pointed at a new
branch\&.
.RE
.PP
cherry\-picking
.RS 4
In
SCM
jargon, "cherry pick" means to choose a subset of changes out of a series of changes (typically commits) and record them as a new series of changes on top of a different codebase\&. In Git, this is performed by the "git cherry\-pick" command to extract the change introduced by an existing
commit
and to record it based on the tip of the current
branch
as a new commit\&.
.RE
.PP
clean
.RS 4
A
working tree
is clean, if it corresponds to the
revision
referenced by the current
head\&. Also see "dirty"\&.
.RE
.PP
commit
.RS 4
As a noun: A single point in the Git history; the entire history of a project is represented as a set of interrelated commits\&. The word "commit" is often used by Git in the same places other revision control systems use the words "revision" or "version"\&. Also used as a short hand for
commit object\&.
.sp
As a verb: The action of storing a new snapshot of the project\(cqs state in the Git history, by creating a new commit representing the current state of the
index
and advancing
HEAD
to point at the new commit\&.
.RE
.PP
commit graph concept, representations and usage
.RS 4
A synonym for the
DAG
structure formed by the commits in the object database,
referenced
by branch tips, using their
chain
of linked commits\&. This structure is the definitive commit graph\&. The graph can be represented in other ways, e\&.g\&. the
"commit\-graph" file\&.
.RE
.PP
commit\-graph file
.RS 4
The "commit\-graph" (normally hyphenated) file is a supplemental representation of the
commit graph
which accelerates commit graph walks\&. The "commit\-graph" file is stored either in the \&.git/objects/info directory or in the info directory of an alternate object database\&.
.RE
.PP
commit object
.RS 4
An
object
which contains the information about a particular
revision, such as
parents, committer, author, date and the
tree object
which corresponds to the top
directory
of the stored revision\&.
.RE
.PP
commit\-ish (also committish)
.RS 4
A
commit object
or an
object
that can be recursively
dereferenced
to a commit object\&. The following are all commit\-ishes: a commit object, a
tag object
that points to a commit object, a tag object that points to a tag object that points to a commit object, etc\&.
.RE
.PP
core Git
.RS 4
Fundamental data structures and utilities of Git\&. Exposes only limited source code management tools\&.
.RE
.PP
DAG
.RS 4
Directed acyclic graph\&. The
commit objects
form a directed acyclic graph, because they have parents (directed), and the graph of commit objects is acyclic (there is no
chain
which begins and ends with the same
object)\&.
.RE
.PP
dangling object
.RS 4
An
unreachable object
which is not
reachable
even from other unreachable objects; a dangling object has no references to it from any reference or
object
in the
repository\&.
.RE
.PP
dereference
.RS 4
Referring to a
symbolic ref: the action of accessing the
reference
pointed at by a symbolic ref\&. Recursive dereferencing involves repeating the aforementioned process on the resulting ref until a non\-symbolic reference is found\&.
.sp
Referring to a
tag object: the action of accessing the
object
a tag points at\&. Tags are recursively dereferenced by repeating the operation on the result object until the result has either a specified
object type
(where applicable) or any non\-"tag" object type\&. A synonym for "recursive dereference" in the context of tags is "peel"\&.
.sp
Referring to a
commit object: the action of accessing the commit\(cqs tree object\&. Commits cannot be dereferenced recursively\&.
.sp
Unless otherwise specified, "dereferencing" as it used in the context of Git commands or protocols is implicitly recursive\&.
.RE
.PP
detached HEAD
.RS 4
Normally the
HEAD
stores the name of a
branch, and commands that operate on the history HEAD represents operate on the history leading to the tip of the branch the HEAD points at\&. However, Git also allows you to
check out
an arbitrary
commit
that isn\(cqt necessarily the tip of any particular branch\&. The HEAD in such a state is called "detached"\&.
.sp
Note that commands that operate on the history of the current branch (e\&.g\&.
\fBgit commit\fR
to build a new history on top of it) still work while the HEAD is detached\&. They update the HEAD to point at the tip of the updated history without affecting any branch\&. Commands that update or inquire information
\fIabout\fR
the current branch (e\&.g\&.
\fBgit branch \-\-set\-upstream\-to\fR
that sets what remote\-tracking branch the current branch integrates with) obviously do not work, as there is no (real) current branch to ask about in this state\&.
.RE
.PP
directory
.RS 4
The list you get with "ls" :\-)
.RE
.PP
dirty
.RS 4
A
working tree
is said to be "dirty" if it contains modifications which have not been
committed
to the current
branch\&.
.RE
.PP
evil merge
.RS 4
An evil merge is a
merge
that introduces changes that do not appear in any
parent\&.
.RE
.PP
fast\-forward
.RS 4
A fast\-forward is a special type of
merge
where you have a
revision
and you are "merging" another
branch\*(Aqs changes that happen to be a descendant of what you have\&. In such a case, you do not make a new
merge
commit
but instead just update your branch to point at the same revision as the branch you are merging\&. This will happen frequently on a
remote\-tracking branch
of a remote
repository\&.
.RE
.PP
fetch
.RS 4
Fetching a
branch
means to get the branch\(cqs
head ref
from a remote
repository, to find out which objects are missing from the local
object database, and to get them, too\&. See also
\fBgit-fetch\fR(1)\&.
.RE
.PP
file system
.RS 4
Linus Torvalds originally designed Git to be a user space file system, i\&.e\&. the infrastructure to hold files and directories\&. That ensured the efficiency and speed of Git\&.
.RE
.PP
Git archive
.RS 4
Synonym for
repository
(for arch people)\&.
.RE
.PP
gitfile
.RS 4
A plain file
\fB\&.git\fR
at the root of a working tree that points at the directory that is the real repository\&. For proper use see
\fBgit-worktree\fR(1)
or
\fBgit-submodule\fR(1)\&. For syntax see
\fBgitrepository-layout\fR(5)\&.
.RE
.PP
grafts
.RS 4
Grafts enable two otherwise different lines of development to be joined together by recording fake ancestry information for commits\&. This way you can make Git pretend the set of
parents
a
commit
has is different from what was recorded when the commit was created\&. Configured via the
\fB\&.git/info/grafts\fR
file\&.
.sp
Note that the grafts mechanism is outdated and can lead to problems transferring objects between repositories; see
\fBgit-replace\fR(1)
for a more flexible and robust system to do the same thing\&.
.RE
.PP
hash
.RS 4
In Git\(cqs context, synonym for
object name\&.
.RE
.PP
head
.RS 4
A
named reference
to the
commit
at the tip of a
branch\&. Heads are stored in a file in
\fB$GIT_DIR/refs/heads/\fR
directory, except when using packed refs\&. (See
\fBgit-pack-refs\fR(1)\&.)
.RE
.PP
HEAD
.RS 4
The current
branch\&. In more detail: Your
working tree
is normally derived from the state of the tree referred to by HEAD\&. HEAD is a reference to one of the
heads
in your repository, except when using a
detached HEAD, in which case it directly references an arbitrary commit\&.
.RE
.PP
head ref
.RS 4
A synonym for
head\&.
.RE
.PP
hook
.RS 4
During the normal execution of several Git commands, call\-outs are made to optional scripts that allow a developer to add functionality or checking\&. Typically, the hooks allow for a command to be pre\-verified and potentially aborted, and allow for a post\-notification after the operation is done\&. The hook scripts are found in the
\fB$GIT_DIR/hooks/\fR
directory, and are enabled by simply removing the
\fB\&.sample\fR
suffix from the filename\&. In earlier versions of Git you had to make them executable\&.
.RE
.PP
index
.RS 4
A collection of files with stat information, whose contents are stored as objects\&. The index is a stored version of your
working tree\&. Truth be told, it can also contain a second, and even a third version of a working tree, which are used when
merging\&.
.RE
.PP
index entry
.RS 4
The information regarding a particular file, stored in the
index\&. An index entry can be unmerged, if a
merge
was started, but not yet finished (i\&.e\&. if the index contains multiple versions of that file)\&.
.RE
.PP
master
.RS 4
The default development
branch\&. Whenever you create a Git
repository, a branch named "master" is created, and becomes the active branch\&. In most cases, this contains the local development, though that is purely by convention and is not required\&.
.RE
.PP
merge
.RS 4
As a verb: To bring the contents of another
branch
(possibly from an external
repository) into the current branch\&. In the case where the merged\-in branch is from a different repository, this is done by first
fetching
the remote branch and then merging the result into the current branch\&. This combination of fetch and merge operations is called a
pull\&. Merging is performed by an automatic process that identifies changes made since the branches diverged, and then applies all those changes together\&. In cases where changes conflict, manual intervention may be required to complete the merge\&.
.sp
As a noun: unless it is a
fast\-forward, a successful merge results in the creation of a new
commit
representing the result of the merge, and having as
parents
the tips of the merged
branches\&. This commit is referred to as a "merge commit", or sometimes just a "merge"\&.
.RE
.PP
object
.RS 4
The unit of storage in Git\&. It is uniquely identified by the
SHA\-1
of its contents\&. Consequently, an object cannot be changed\&.
.RE
.PP
object database
.RS 4
Stores a set of "objects", and an individual
object
is identified by its
object name\&. The objects usually live in
\fB$GIT_DIR/objects/\fR\&.
.RE
.PP
object identifier (oid)
.RS 4
Synonym for
object name\&.
.RE
.PP
object name
.RS 4
The unique identifier of an
object\&. The object name is usually represented by a 40 character hexadecimal string\&. Also colloquially called
SHA\-1\&.
.RE
.PP
object type
.RS 4
One of the identifiers "commit", "tree", "tag" or "blob" describing the type of an
object\&.
.RE
.PP
octopus
.RS 4
To
merge
more than two
branches\&.
.RE
.PP
orphan
.RS 4
The act of getting on a
branch
that does not exist yet (i\&.e\&., an
unborn
branch)\&. After such an operation, the commit first created becomes a commit without a parent, starting a new history\&.
.RE
.PP
origin
.RS 4
The default upstream
repository\&. Most projects have at least one upstream project which they track\&. By default
\fIorigin\fR
is used for that purpose\&. New upstream updates will be fetched into
remote\-tracking branches
named origin/name\-of\-upstream\-branch, which you can see using
\fBgit branch \-r\fR\&.
.RE
.PP
overlay
.RS 4
Only update and add files to the working directory, but don\(cqt delete them, similar to how
\fIcp \-R\fR
would update the contents in the destination directory\&. This is the default mode in a
checkout
when checking out files from the
index
or a
tree\-ish\&. In contrast, no\-overlay mode also deletes tracked files not present in the source, similar to
\fIrsync \-\-delete\fR\&.
.RE
.PP
pack
.RS 4
A set of objects which have been compressed into one file (to save space or to transmit them efficiently)\&.
.RE
.PP
pack index
.RS 4
The list of identifiers, and other information, of the objects in a
pack, to assist in efficiently accessing the contents of a pack\&.
.RE
.PP
pathspec
.RS 4
Pattern used to limit paths in Git commands\&.
.sp
Pathspecs are used on the command line of "git ls\-files", "git ls\-tree", "git add", "git grep", "git diff", "git checkout", and many other commands to limit the scope of operations to some subset of the tree or working tree\&. See the documentation of each command for whether paths are relative to the current directory or toplevel\&. The pathspec syntax is as follows:
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
any path matches itself
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
the pathspec up to the last slash represents a directory prefix\&. The scope of that pathspec is limited to that subtree\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
the rest of the pathspec is a pattern for the remainder of the pathname\&. Paths relative to the directory prefix will be matched against that pattern using fnmatch(3); in particular,
\fI*\fR
and
\fI?\fR
\fIcan\fR
match directory separators\&.
.RE
.sp
For example, Documentation/*\&.jpg will match all \&.jpg files in the Documentation subtree, including Documentation/chapter_1/figure_1\&.jpg\&.
.sp
A pathspec that begins with a colon
\fB:\fR
has special meaning\&. In the short form, the leading colon
\fB:\fR
is followed by zero or more "magic signature" letters (which optionally is terminated by another colon
\fB:\fR), and the remainder is the pattern to match against the path\&. The "magic signature" consists of ASCII symbols that are neither alphanumeric, glob, regex special characters nor colon\&. The optional colon that terminates the "magic signature" can be omitted if the pattern begins with a character that does not belong to "magic signature" symbol set and is not a colon\&.
.sp
In the long form, the leading colon
\fB:\fR
is followed by an open parenthesis
\fB(\fR, a comma\-separated list of zero or more "magic words", and a close parentheses
\fB)\fR, and the remainder is the pattern to match against the path\&.
.sp
A pathspec with only a colon means "there is no pathspec"\&. This form should not be combined with other pathspec\&.
.PP
top
.RS 4
The magic word
\fBtop\fR
(magic signature:
\fB/\fR) makes the pattern match from the root of the working tree, even when you are running the command from inside a subdirectory\&.
.RE
.PP
literal
.RS 4
Wildcards in the pattern such as
\fB*\fR
or
\fB?\fR
are treated as literal characters\&.
.RE
.PP
icase
.RS 4
Case insensitive match\&.
.RE
.PP
glob
.RS 4
Git treats the pattern as a shell glob suitable for consumption by fnmatch(3) with the FNM_PATHNAME flag: wildcards in the pattern will not match a / in the pathname\&. For example, "Documentation/*\&.html" matches "Documentation/git\&.html" but not "Documentation/ppc/ppc\&.html" or "tools/perf/Documentation/perf\&.html"\&.
.sp
Two consecutive asterisks ("\fB**\fR") in patterns matched against full pathname may have special meaning:
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
A leading "\fB**\fR" followed by a slash means match in all directories\&. For example, "\fB**/foo\fR" matches file or directory "\fBfoo\fR" anywhere, the same as pattern "\fBfoo\fR"\&. "\fB**/foo/bar\fR" matches file or directory "\fBbar\fR" anywhere that is directly under directory "\fBfoo\fR"\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
A trailing "\fB/**\fR" matches everything inside\&. For example, "\fBabc/**\fR" matches all files inside directory "abc", relative to the location of the
\fB\&.gitignore\fR
file, with infinite depth\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
A slash followed by two consecutive asterisks then a slash matches zero or more directories\&. For example, "\fBa/**/b\fR" matches "\fBa/b\fR", "\fBa/x/b\fR", "\fBa/x/y/b\fR" and so on\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Other consecutive asterisks are considered invalid\&.
.sp
Glob magic is incompatible with literal magic\&.
.RE
.RE
.PP
attr
.RS 4
After
\fBattr:\fR
comes a space separated list of "attribute requirements", all of which must be met in order for the path to be considered a match; this is in addition to the usual non\-magic pathspec pattern matching\&. See
\fBgitattributes\fR(5)\&.
.sp
Each of the attribute requirements for the path takes one of these forms:
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
"\fBATTR\fR" requires that the attribute
\fBATTR\fR
be set\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
"\fB\-ATTR\fR" requires that the attribute
\fBATTR\fR
be unset\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
"\fBATTR=VALUE\fR" requires that the attribute
\fBATTR\fR
be set to the string
\fBVALUE\fR\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
"\fB!ATTR\fR" requires that the attribute
\fBATTR\fR
be unspecified\&.
.sp
Note that when matching against a tree object, attributes are still obtained from working tree, not from the given tree object\&.
.RE
.RE
.PP
exclude
.RS 4
After a path matches any non\-exclude pathspec, it will be run through all exclude pathspecs (magic signature:
\fB!\fR
or its synonym
\fB^\fR)\&. If it matches, the path is ignored\&. When there is no non\-exclude pathspec, the exclusion is applied to the result set as if invoked without any pathspec\&.
.RE
.RE
.PP
parent
.RS 4
A
commit object
contains a (possibly empty) list of the logical predecessor(s) in the line of development, i\&.e\&. its parents\&.
.RE
.PP
peel
.RS 4
The action of recursively
dereferencing
a
tag object\&.
.RE
.PP
pickaxe
.RS 4
The term
pickaxe
refers to an option to the diffcore routines that help select changes that add or delete a given text string\&. With the
\fB\-\-pickaxe\-all\fR
option, it can be used to view the full
changeset
that introduced or removed, say, a particular line of text\&. See
\fBgit-diff\fR(1)\&.
.RE
.PP
plumbing
.RS 4
Cute name for
core Git\&.
.RE
.PP
porcelain
.RS 4
Cute name for programs and program suites depending on
core Git, presenting a high level access to core Git\&. Porcelains expose more of a
SCM
interface than the
plumbing\&.
.RE
.PP
per\-worktree ref
.RS 4
Refs that are per\-worktree, rather than global\&. This is presently only
HEAD
and any refs that start with
\fBrefs/bisect/\fR, but might later include other unusual refs\&.
.RE
.PP
pseudoref
.RS 4
Pseudorefs are a class of files under
\fB$GIT_DIR\fR
which behave like refs for the purposes of rev\-parse, but which are treated specially by git\&. Pseudorefs both have names that are all\-caps, and always start with a line consisting of a
SHA\-1
followed by whitespace\&. So, HEAD is not a pseudoref, because it is sometimes a symbolic ref\&. They might optionally contain some additional data\&.
\fBMERGE_HEAD\fR
and
\fBCHERRY_PICK_HEAD\fR
are examples\&. Unlike
per\-worktree refs, these files cannot be symbolic refs, and never have reflogs\&. They also cannot be updated through the normal ref update machinery\&. Instead, they are updated by directly writing to the files\&. However, they can be read as if they were refs, so
\fBgit rev\-parse MERGE_HEAD\fR
will work\&.
.RE
.PP
pull
.RS 4
Pulling a
branch
means to
fetch
it and
merge
it\&. See also
\fBgit-pull\fR(1)\&.
.RE
.PP
push
.RS 4
Pushing a
branch
means to get the branch\(cqs
head ref
from a remote
repository, find out if it is an ancestor to the branch\(cqs local head ref, and in that case, putting all objects, which are
reachable
from the local head ref, and which are missing from the remote repository, into the remote
object database, and updating the remote head ref\&. If the remote
head
is not an ancestor to the local head, the push fails\&.
.RE
.PP
reachable
.RS 4
All of the ancestors of a given
commit
are said to be "reachable" from that commit\&. More generally, one
object
is reachable from another if we can reach the one from the other by a
chain
that follows
tags
to whatever they tag,
commits
to their parents or trees, and
trees
to the trees or
blobs
that they contain\&.
.RE
.PP
reachability bitmaps
.RS 4
Reachability bitmaps store information about the
reachability
of a selected set of commits in a packfile, or a multi\-pack index (MIDX), to speed up object search\&. The bitmaps are stored in a "\&.bitmap" file\&. A repository may have at most one bitmap file in use\&. The bitmap file may belong to either one pack, or the repository\(cqs multi\-pack index (if it exists)\&.
.RE
.PP
rebase
.RS 4
To reapply a series of changes from a
branch
to a different base, and reset the
head
of that branch to the result\&.
.RE
.PP
ref
.RS 4
A name that begins with
\fBrefs/\fR
(e\&.g\&.
\fBrefs/heads/master\fR) that points to an
object name
or another ref (the latter is called a
symbolic ref)\&. For convenience, a ref can sometimes be abbreviated when used as an argument to a Git command; see
\fBgitrevisions\fR(7)
for details\&. Refs are stored in the
repository\&.
.sp
The ref namespace is hierarchical\&. Different subhierarchies are used for different purposes (e\&.g\&. the
\fBrefs/heads/\fR
hierarchy is used to represent local branches)\&.
.sp
There are a few special\-purpose refs that do not begin with
\fBrefs/\fR\&. The most notable example is
\fBHEAD\fR\&.
.RE
.PP
reflog
.RS 4
A reflog shows the local "history" of a ref\&. In other words, it can tell you what the 3rd last revision in
\fIthis\fR
repository was, and what was the current state in
\fIthis\fR
repository, yesterday 9:14pm\&. See
\fBgit-reflog\fR(1)
for details\&.
.RE
.PP
refspec
.RS 4
A "refspec" is used by
fetch
and
push
to describe the mapping between remote
ref
and local ref\&.
.RE
.PP
remote repository
.RS 4
A
repository
which is used to track the same project but resides somewhere else\&. To communicate with remotes, see
fetch
or
push\&.
.RE
.PP
remote\-tracking branch
.RS 4
A
ref
that is used to follow changes from another
repository\&. It typically looks like
\fIrefs/remotes/foo/bar\fR
(indicating that it tracks a branch named
\fIbar\fR
in a remote named
\fIfoo\fR), and matches the right\-hand\-side of a configured fetch
refspec\&. A remote\-tracking branch should not contain direct modifications or have local commits made to it\&.
.RE
.PP
repository
.RS 4
A collection of
refs
together with an
object database
containing all objects which are
reachable
from the refs, possibly accompanied by meta data from one or more
porcelains\&. A repository can share an object database with other repositories via
alternates mechanism\&.
.RE
.PP
resolve
.RS 4
The action of fixing up manually what a failed automatic
merge
left behind\&.
.RE
.PP
revision
.RS 4
Synonym for
commit
(the noun)\&.
.RE
.PP
rewind
.RS 4
To throw away part of the development, i\&.e\&. to assign the
head
to an earlier
revision\&.
.RE
.PP
SCM
.RS 4
Source code management (tool)\&.
.RE
.PP
SHA\-1
.RS 4
"Secure Hash Algorithm 1"; a cryptographic hash function\&. In the context of Git used as a synonym for
object name\&.
.RE
.PP
shallow clone
.RS 4
Mostly a synonym to
shallow repository
but the phrase makes it more explicit that it was created by running
\fBgit clone \-\-depth=\&.\&.\&.\fR
command\&.
.RE
.PP
shallow repository
.RS 4
A shallow
repository
has an incomplete history some of whose
commits
have
parents
cauterized away (in other words, Git is told to pretend that these commits do not have the parents, even though they are recorded in the
commit object)\&. This is sometimes useful when you are interested only in the recent history of a project even though the real history recorded in the upstream is much larger\&. A shallow repository is created by giving the
\fB\-\-depth\fR
option to
\fBgit-clone\fR(1), and its history can be later deepened with
\fBgit-fetch\fR(1)\&.
.RE
.PP
stash entry
.RS 4
An
object
used to temporarily store the contents of a
dirty
working directory and the index for future reuse\&.
.RE
.PP
special ref
.RS 4
A ref that has different semantics than normal refs\&. These refs can be accessed via normal Git commands but may not behave the same as a normal ref in some cases\&.
.sp
The following special refs are known to Git:
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
"\fBFETCH_HEAD\fR" is written by
\fBgit-fetch\fR(1)
or
\fBgit-pull\fR(1)\&. It may refer to multiple object IDs\&. Each object ID is annotated with metadata indicating where it was fetched from and its fetch status\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
"\fBMERGE_HEAD\fR" is written by
\fBgit-merge\fR(1)
when resolving merge conflicts\&. It contains all commit IDs which are being merged\&.
.RE
.RE
.PP
submodule
.RS 4
A
repository
that holds the history of a separate project inside another repository (the latter of which is called
superproject)\&.
.RE
.PP
superproject
.RS 4
A
repository
that references repositories of other projects in its working tree as
submodules\&. The superproject knows about the names of (but does not hold copies of) commit objects of the contained submodules\&.
.RE
.PP
symref
.RS 4
Symbolic reference: instead of containing the
SHA\-1
id itself, it is of the format
\fIref: refs/some/thing\fR
and when referenced, it recursively
dereferences
to this reference\&.
\fIHEAD\fR
is a prime example of a symref\&. Symbolic references are manipulated with the
\fBgit-symbolic-ref\fR(1)
command\&.
.RE
.PP
tag
.RS 4
A
ref
under
\fBrefs/tags/\fR
namespace that points to an object of an arbitrary type (typically a tag points to either a
tag
or a
commit object)\&. In contrast to a
head, a tag is not updated by the
\fBcommit\fR
command\&. A Git tag has nothing to do with a Lisp tag (which would be called an
object type
in Git\(cqs context)\&. A tag is most typically used to mark a particular point in the commit ancestry
chain\&.
.RE
.PP
tag object
.RS 4
An
object
containing a
ref
pointing to another object, which can contain a message just like a
commit object\&. It can also contain a (PGP) signature, in which case it is called a "signed tag object"\&.
.RE
.PP
topic branch
.RS 4
A regular Git
branch
that is used by a developer to identify a conceptual line of development\&. Since branches are very easy and inexpensive, it is often desirable to have several small branches that each contain very well defined concepts or small incremental yet related changes\&.
.RE
.PP
tree
.RS 4
Either a
working tree, or a
tree object
together with the dependent
blob
and tree objects (i\&.e\&. a stored representation of a working tree)\&.
.RE
.PP
tree object
.RS 4
An
object
containing a list of file names and modes along with refs to the associated blob and/or tree objects\&. A
tree
is equivalent to a
directory\&.
.RE
.PP
tree\-ish (also treeish)
.RS 4
A
tree object
or an
object
that can be recursively
dereferenced
to a tree object\&. Dereferencing a
commit object
yields the tree object corresponding to the
revision\*(Aqs top
directory\&. The following are all tree\-ishes: a
commit\-ish, a tree object, a
tag object
that points to a tree object, a tag object that points to a tag object that points to a tree object, etc\&.
.RE
.PP
unborn
.RS 4
The
HEAD
can point at a
branch
that does not yet exist and that does not have any commit on it yet, and such a branch is called an unborn branch\&. The most typical way users encounter an unborn branch is by creating a repository anew without cloning from elsewhere\&. The HEAD would point at the
\fImain\fR
(or
\fImaster\fR, depending on your configuration) branch that is yet to be born\&. Also some operations can get you on an unborn branch with their
orphan
option\&.
.RE
.PP
unmerged index
.RS 4
An
index
which contains unmerged
index entries\&.
.RE
.PP
unreachable object
.RS 4
An
object
which is not
reachable
from a
branch,
tag, or any other reference\&.
.RE
.PP
upstream branch
.RS 4
The default
branch
that is merged into the branch in question (or the branch in question is rebased onto)\&. It is configured via branch\&.<name>\&.remote and branch\&.<name>\&.merge\&. If the upstream branch of
\fIA\fR
is
\fIorigin/B\fR
sometimes we say "\fIA\fR
is tracking
\fIorigin/B\fR"\&.
.RE
.PP
working tree
.RS 4
The tree of actual checked out files\&. The working tree normally contains the contents of the
HEAD
commit\(cqs tree, plus any local changes that you have made but not yet committed\&.
.RE
.PP
worktree
.RS 4
A repository can have zero (i\&.e\&. bare repository) or one or more worktrees attached to it\&. One "worktree" consists of a "working tree" and repository metadata, most of which are shared among other worktrees of a single repository, and some of which are maintained separately per worktree (e\&.g\&. the index, HEAD and pseudorefs like MERGE_HEAD, per\-worktree refs and per\-worktree configuration file)\&.
.RE
.SH "SEE ALSO"
.sp
\fBgittutorial\fR(7), \fBgittutorial-2\fR(7), \fBgitcvs-migration\fR(7), \fBgiteveryday\fR(7), \m[blue]\fBThe Git User\(cqs Manual\fR\m[]\&\s-2\u[1]\d\s+2
.SH "GIT"
.sp
Part of the \fBgit\fR(1) suite
.SH "NOTES"
.IP " 1." 4
The Git User\(cqs Manual
.RS 4
\%git-htmldocs/user-manual.html
.RE