#!/usr/bin/perl
my $ouput = `egrep -f patternfile testfile > output`;
print "$output\n";  

##</code><code>##

#!/usr/bin/perl
my $p = 'patternfile';
my $t = 'testfile';
my $o = 'output';

my $ouput = `egrep -f $p $t > $o`;
print "$output\n";