iankelling.org Git - small-misc-bash/blob - isdiff

   1 #!/bin/bash
   2 # I, Ian Kelling, follow the GNU license recommendations at
   3 # https://www.gnu.org/licenses/license-recommendations.en.html. They
   4 # recommend that small programs, < 300 lines, be licensed under the
   5 # Apache License 2.0. This file contains or is part of one or more small
   6 # programs. If a small program grows beyond 300 lines, I plan to switch
   7 # its license to GPL.
   8
   9 # Copyright 2024 Ian Kelling
  10
  11 # Licensed under the Apache License, Version 2.0 (the "License");
  12 # you may not use this file except in compliance with the License.
  13 # You may obtain a copy of the License at
  14
  15 #     http://www.apache.org/licenses/LICENSE-2.0
  16
  17 # Unless required by applicable law or agreed to in writing, software
  18 # distributed under the License is distributed on an "AS IS" BASIS,
  19 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  20 # See the License for the specific language governing permissions and
  21 # limitations under the License.
  22
  23
  24 isdiff() {
  25     local help="Usage: isdiff [--help|-h] [-v] [-x] FILE1 FILE2
  26 Test if FILE1 and FILE2 have the same contents
  27
  28 Returns 0 for same, 1 for diff, 2 for error.
  29
  30 -v   verbose
  31 -r   use most reliable checksum available, ie. sha instead of md5"
  32
  33     local v x y reliable
  34     while true; do
  35         if [[ $1 == --help ]]  || [[ $1 == -[^-]* && $1 == *h* ]]; then
  36             echo "$help"
  37             return
  38         elif [[ $1 == -[^-]* && $1 == *v* ]]; then
  39             v=true
  40             shift
  41         elif [[ $1 == -[^-]* && $1 == *r* ]]; then
  42             reliable=true
  43             shift
  44         else
  45             break
  46         fi
  47     done
  48
  49     x=($(type -p sha512sum) $(type -p sha256sum) $(type -p sha1sum) $(type -p md5sum))
  50     if [[ $reliable ]]; then
  51         sumbinary=$x
  52     else
  53         sumbinary=${x[${#x[@]}-1]}
  54     fi
  55
  56     [[ $sumbinary ]] || {
  57         echo "Need 1 of sha512sum sha256sum sha1sum or md5sum for sum() function"
  58         return 1
  59     }
  60     if [[ $# != 2 ]]; then
  61         [[ $v ]] && echo Error: need 2 arguments.
  62         return 2
  63     fi
  64     if [[ $v ]]; then
  65         x=$($sumbinary < "$1" ) || return 2
  66         y=$($sumbinary < "$2" ) || return 2
  67     else
  68         { x=$($sumbinary < "$1" ) ;} 2>/dev/null || return 2
  69         { y=$($sumbinary < "$2" ) ;} 2>/dev/null || return 2
  70     fi
  71     if [[  $x == "$y" ]]; then
  72         return 1 # same
  73     else
  74         [[ $v ]] && echo "$1" "$2" different.
  75         return 0
  76     fi
  77 }
  78 isdiff "$@"