I have a script which does some basic awk like filtering using a while(<>) loop. I want the script to be able to display usage and version, but otherwise assume all arguments are files. How do I combine getopt with the <> operator?
As others have mentioned, Getopt::Long is the prefered module. It has been around since Perl 3.x.
There's a lot of options, and it can take a while to get use to the syntax, but it does exactly what you want:
use strict;
use warnings;
use Getopt::Long;
use feature qw(say);
use Pod::Usage;
my ( $version, $help ); #Strict, we have to predeclare these:
GetOptions(
'help' => \$help,
'version' => \$version,
) or pod2usage ( -message => "Invalid options" );
That's all there is to it. When the Getoptions subroutine runs, it will parse your command line (the @ARGV array) for anything that starts with a - or --. It will process those, and when it comes to either a double dash by itself, or an option not starting with a dash, it will assume those are files and it's done processing. At that point, all of the option strings (and their parameters) have been shifted out of the @ARGSV array, and you're left with your files:
if ( $help ) {
pod2usage;
}
if ( $version ) {
say "Version 1.23.3";
exit;
}
while ( my $file = <>) {
...
}
Getopts::Long is part of the standard Perl installation, so it should always be available to you.
I know many people are wary of using these modules because they think they're not standard Perl, but they are just as much a part of Perl as commands like print and chomp. Perl comes with over 500 of them and they're yours to use.