cpio.sh

   1 #!/bin/sh
   2 #
   3 # Emulates some cpio behavior using GNU tar
   4
   5 die() {
   6         echo >&2 "$@"
   7         exit 1
   8 }
   9
  10 null=
  11
  12 while test $# -gt 0; do
  13         case "$1" in
  14         -0)     null=--null;;
  15         -o)     mode=o;;
  16         -iuv)   ;;
  17         -pumd|-pumdl)
  18                 mode=p
  19                 dir="$2"
  20                 shift
  21                 ;;
  22         *)      die "cpio emulation supports only -0, -o, -iuv, -pumdl";;
  23         esac
  24         shift
  25 done
  26
  27 prev=
  28
  29 filterdirs() {
  30         while read f; do
  31                 if test -d "$f"; then
  32                         # list only empty directories
  33                         # here we assume that directories are listed after
  34                         # its files (aka 'find -depth'), hence, a directory
  35                         # that is not empty will be a leading sub-string
  36                         # of the preceding entry
  37                         case "$prev" in
  38                         "$f"/* ) ;;
  39                         *) echo "$f";;
  40                         esac
  41                 else
  42                         echo "$f"
  43                 fi
  44                 prev="$f"
  45         done
  46 }
  47
  48 case $mode in
  49 o)
  50         tar --create --file=- $null --files-from=-
  51         ;;
  52 p)
  53         test -z "$null" || die "cpio: cannot use -0 in pass-through mode"
  54         filterdirs |
  55         tar --create --file=- --files-from=- |
  56         tar --extract --directory="$dir" --file=-
  57         ;;
  58 *)
  59         tar xvf -
  60 esac