shell, perl, performance, parallelism, profiling, etc. (was: Upgrade guidance)

[Ben Scott]

On Tue, Oct 21, 2008 at 6:51 PM, Ben Scott <dragonhawk at gmail.com> wrote:
>  Challenge accepted.... okay, intersect.pl will follow in a separate message.

#!/usr/bin/perl -w

# intersect.pl
# Gives the intersection of two text files (lines contained in both files).
# Similar to comm(1), but does not require sorted input.
# Specify input files as command arguments.

# Provided free of charge, without restriction on use, modification, or
# redistribution.  No warranty.  Use at your own risk.

use strict;
use warnings FATAL=>'all';
use Fatal qw (open close);

use constant PRESENT => 1;

my (%one, %two);

open FH, "<$ARGV[0]";
$one{$_} = PRESENT while (<FH>);
close FH;

open FH, "<$ARGV[1]";
$two{$_} = PRESENT while (<FH>);
close FH;

foreach my $one (keys %one) {
  if (defined $two{$one}) {
    print $one;
    }
  }

# EOF intersect.pl