user-tools/ffilt

   1 #!/bin/bash
   2
   3 true <<'EOF'
   4 =pod
   5
   6 =head1 NAME
   7
   8 ffilt - Filter a file via a command's STDIO and write back to it
   9
  10 =head1 SYNOPSIS
  11
  12 ffilt I<FILE> I<COMMAND> [I<ARGS>]
  13
  14 =head1 DESCRIPTION
  15
  16 Feed I<FILE> into I<COMMAND>'s stdin, then save its stdout back to I<FILE>
  17 if I<COMMAND> ran successfully.
  18
  19 Similar to this shell script:
  20
  21  output=`cat I<FILE> | I<COMMAND>`
  22  [ $? = 0 ] && echo "$output" > I<FILE>
  23
  24 =head1 LIMITATIONS
  25
  26 =head1 SEE ALSO
  27
  28 sponge(1), insitu(1) L<https://github.com/athas/insitu>
  29
  30 =cut
  31
  32 EOF
  33
  34
  35 set -e
  36 set -o pipefail
  37 set -u
  38
  39 . /usr/lib/tool/bash-utils
  40
  41
  42 opt_verbose=no
  43
  44
  45 while [ $# != 0 ]
  46 do
  47         case "$1" in
  48         --help)
  49                 pod2text "$0"
  50                 exit 0;;
  51         -v|--verbose)
  52                 opt_verbose=yes
  53                 ;;
  54         --)
  55                 shift
  56                 break;;
  57         -*)
  58                 errx -1 "unknown option: $1";;
  59         *)
  60                 break;;
  61         esac
  62         shift
  63 done
  64
  65 set -e
  66 set -o pipefail
  67 set -u
  68
  69 file=$1
  70 shift
  71
  72 stdout=`cat "$file" | command "$@"`
  73 # pipefail make us die here if either cat or command failed
  74 cat > "$file" <<< "$stdout"