support/mnt-excl

   1 #!/usr/bin/env perl
   2 # This script takes a command-line arg of a source directory
   3 # that will be passed to rsync, and generates a set of excludes
   4 # that will exclude all mount points from the list.  This is
   5 # useful if you have "bind" mounts since the --one-file-system
   6 # option won't notice the transition to a different spot on
   7 # the same disk.  For example:
   8 #
   9 # mnt-excl /dir | rsync --exclude-from=- ... /dir /dest/
  10 # mnt-excl /dir/ | rsync --exclude-from=- ... /dir/ /dest/
  11 # ssh host mnt-excl /dir | rsync --exclude-from=- ... host:/dir /dest/
  12 #
  13 # Imagine that /dir/foo is a mount point: the first invocation of
  14 # mnt-excl would have output /dir/foo, while the second would have
  15 # output /foo (which are the properly anchored excludes).
  16 #
  17 # NOTE:  This script expects /proc/mounts to exist, but could be
  18 # easily adapted to read /etc/mtab or similar.
  19 #
  20 # ADDENDUM:  The addition of the --filter option (which has support for
  21 # absolute-anchored excludes) can make this script unneeded in some
  22 # scenarios.  If you don't need delete protection on the receiving side
  23 # (or if the destination path is identical to the source path), then you
  24 # can exclude some absolute paths from the transfer based on the mount
  25 # dirs.  For instance:
  26 #
  27 # awk '{print $2}' /proc/mounts | grep -v '^/$' | \
  28 #   rsync -avf 'merge,/- -' /dir host:/dest/
  29
  30 use strict;
  31 use warnings;
  32 use Cwd 'abs_path';
  33
  34 my $file = '/proc/mounts';
  35 my $dir = shift || '/';
  36 my $trailing_slash = $dir =~ m{./$} ? '/' : '';
  37 $dir = abs_path($dir) . $trailing_slash;
  38 $dir =~ s{([^/]*)$}{};
  39 my $trailing = $1;
  40 $trailing = '' if $trailing eq '.' || !-d "$dir$trailing";
  41 $trailing .= '/' if $trailing ne '';
  42
  43 open(IN, $file) or die "Unable to open $file: $!\n";
  44 while (<IN>) {
  45     $_ = (split)[1];
  46     next unless s{^\Q$dir$trailing\E}{}o && $_ ne '';
  47     print "- /$trailing$_\n";
  48 }
  49 close IN;