not

   1 #!/usr/bin/perl
   2
   3 =head1 NAME
   4
   5 not - print lines that are present in one file but not another
   6
   7 =head1 SYNOPSIS
   8
   9 not file
  10
  11 not [file|-] [file|-] ...
  12
  13 =head1 DESCRIPTION
  14
  15 B<not> reads the specified files and prints out the lines that are present
  16 in the first but not in subsequent files. Use "-" to make it read a file
  17 from standard input. If only one file is specified, B<not> first reads
  18 standard input, and compares it with the specified file.
  19
  20 =head1 AUTHOR
  21
  22 Copyright 2006 by Joey Hess <joey@kitenet.net>
  23
  24 Licensed under the GNU GPL.
  25
  26 =cut
  27
  28 use warnings;
  29 use strict;
  30
  31 if (@ARGV == 0) {
  32         die "usage: not [file|-] [file|-] ...\n";
  33 }
  34
  35 if (@ARGV == 1) {
  36         unshift @ARGV, "-";
  37 }
  38
  39 my $first=shift;
  40
  41 my %seen;
  42 foreach my $fn (@ARGV) {
  43         open (IN, $fn) || die "and: read $fn: $!\n";
  44         while (<IN>) {
  45                 chomp;
  46                 $seen{$_}++;
  47         }
  48         close IN;
  49 }
  50
  51
  52 open (IN, $first) || die "and: read $first: $!\n";
  53 while (<IN>) {
  54         chomp;
  55         print "$_\n" if ! $seen{$_};
  56 }
  57 close IN;