#!/usr/bin/perl -w

    use strict;


    die "Usage: $0 subset serial\n" unless @ARGV == 2;

    my $subset = shift;
    my $serial = shift;

    open SUBSET, $subset or die "Couldn't open $subset: $!\n";
    open SERIAL, $serial or die "Couldn't open $serial: $!\n";


    while (<SUBSET>) {

        my $subset_num = $_;
        my $serial_num;

        print $serial_num while ($serial_num = <SERIAL>) < $subset_num;
    }

    print while <SERIAL>;


    __END__





##</code><code>##

    #!/usr/bin/perl -w

    use strict;


    die "Usage: $0 subset serial\n" unless @ARGV == 2;

    my $subset = shift;
    my $serial = shift;

    open SUBSET, $subset or die "Couldn't open $subset: $!\n";
    open SERIAL, $serial or die "Couldn't open $serial: $!\n";


    my %used;

    $used{$_}++ while <SUBSET>;

    while (<SERIAL>) {print unless $used{$_}}


    __END__


##</code><code>##






# Find the version number of a module
perl -le 'eval "require $ARGV[0]" and print $ARGV[0]->VERSION' Some::Module


# Check if a module is installed
perl -le 'print 0 + eval "require $ARGV[0]" ' Some::Module

# Or this mnemonic cheat
perl -exists -MSome::Module


# Plain silly
$ perl -wevest
String vest may clash with future fashion at -e line 1.