All this scratching is making me itch.

For scratch. Print serial numbers from a file that are not included in another "subset" file. Both files must be sorted:

#!/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__
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The following works for unsorted files but is less efficient than the above example:

#!/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__
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# Find the version number of a module perl -le 'eval "require $ARGV[0]" and print $ARGV[0]->VERSION' Some::M +odule # 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.
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