move-if-change

   1 #!/bin/sh
   2 # Like mv $1 $2, but if the files are the same, just delete $1.
   3 # Status is zero if successful, nonzero otherwise.
   4
   5 VERSION='2011-01-28 20:09'; # UTC
   6 # The definition above must lie within the first 8 lines in order
   7 # for the Emacs time-stamp write hook (at end) to update it.
   8 # If you change this file with Emacs, please let the write hook
   9 # do its job.  Otherwise, update this string manually.
  10
  11 # Copyright (C) 2002-2007, 2009-2011 Free Software Foundation, Inc.
  12
  13 # This program is free software: you can redistribute it and/or modify
  14 # it under the terms of the GNU General Public License as published by
  15 # the Free Software Foundation, either version 3 of the License, or
  16 # (at your option) any later version.
  17
  18 # This program is distributed in the hope that it will be useful,
  19 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 # GNU General Public License for more details.
  22
  23 # You should have received a copy of the GNU General Public License
  24 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  25
  26 usage="usage: $0 SOURCE DEST"
  27
  28 help="$usage
  29   or:  $0 OPTION
  30 If SOURCE is different than DEST, then move it to DEST; else remove SOURCE.
  31
  32   --help     display this help and exit
  33   --version  output version information and exit
  34
  35 The variable CMPPROG can be used to specify an alternative to \`cmp'.
  36
  37 Report bugs to <bug-gnulib@gnu.org>."
  38
  39 version=`expr "$VERSION" : '\([^ ]*\)'`
  40 version="move-if-change (gnulib) $version
  41 Copyright (C) 2011 Free Software Foundation, Inc.
  42 License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
  43 This is free software: you are free to change and redistribute it.
  44 There is NO WARRANTY, to the extent permitted by law."
  45
  46 cmpprog=${CMPPROG-cmp}
  47
  48 for arg
  49 do
  50   case $arg in
  51     --help | --hel | --he | --h)
  52       exec echo "$help" ;;
  53     --version | --versio | --versi | --vers | --ver | --ve | --v)
  54       exec echo "$version" ;;
  55     --)
  56       shift
  57       break ;;
  58     -*)
  59       echo "$0: invalid option: $arg" >&2
  60       exit 1 ;;
  61     *)
  62       break ;;
  63   esac
  64 done
  65
  66 test $# -eq 2 || { echo "$0: $usage" >&2; exit 1; }
  67
  68 if test -r "$2" && $cmpprog -- "$1" "$2" >/dev/null; then
  69   rm -f -- "$1"
  70 else
  71   if mv -f -- "$1" "$2"; then :; else
  72     # Ignore failure due to a concurrent move-if-change.
  73     test -r "$2" && $cmpprog -- "$1" "$2" >/dev/null && rm -f -- "$1"
  74   fi
  75 fi
  76
  77 ## Local Variables:
  78 ## eval: (add-hook 'write-file-hooks 'time-stamp)
  79 ## time-stamp-start: "VERSION='"
  80 ## time-stamp-format: "%:y-%02m-%02d %02H:%02M"
  81 ## time-stamp-time-zone: "UTC"
  82 ## time-stamp-end: "'; # UTC"
  83 ## End: