Shell Programming and Scripting

#!/bin/ksh
while read line
do
   echo $line
   grep -c $line $mydatafile2
   if [ $? -ne 0 ]; then
       echo "$line not in file2"
   fi
done < $mydatafile1

join -v 1 file1 file2

sort -u file1 > file1x && sort -u file2 > file2x && join -v 1 file1x file2x

[32]/home/t690177> cat arq1 
1 
2 
3 
[32]/home/t690177> cat arq2 
2 
[32]/home/t690177> join -v 1 arq1 arq2
1 
3 
[32]/home/t690177>

file1:

apples
pears
oranges

file2:

apples

m1.pl

#!/usr/bin/perl
while (<>) {
    chomp;
    if ($ARGV=~/file2/) {
        $keys{$_}++;
    } else {
        print "$_\n" if (! $keys {$_});
    }
}

$ ./m1.pl file2 file1
pears
oranges

m2.pl

#!/usr/bin/perl

open FILE, "< $ARGV[1]" or die "Can't find $ARGV[1]: $!";
while (<FILE>) {
    chomp;
    $keys{$_}++;
}
close FILE;

open FILE, "< $ARGV[0]" or die "Can't find $ARGV[0]: $!";
while (<FILE>) {
    chomp;
    print "$_\n" if (! $keys {$_});
}
close FILE;

$ ./m2.pl file1 file2
pears
oranges

grep -vif file1 file2 > new_file