Write a module:

package Vasuperl;

use strict;
use warnings;
use Exporter;
use vars qw($VERSION @ISA @EXPORT_OK );

$VERSION   = 1.00;
@ISA       = qw(Exporter);
@EXPORT_OK = qw(parse_log);

sub parse_log {
    my ( $log_file, $pattern ) = @_;
    # parse your log
    # and return something useful
}

1;
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Use it:

#!/usr/bin/env perl

use strict;
use warnings;
use lib q(.);
use Vasuperl qw (parse_log);

my $log_file = shift || die $!;
my $pattern  = qr(.);
my $result   = parse_log( $log_file, $pattern );
# do something with $result

__END__
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Update: Changed legacy code on special request by choroba:

package Vasuperl;

use strict;
use warnings;
use Exporter qw(import);

our ( $VERSION, @EXPORT_OK );

$VERSION   = 1.01;
@EXPORT_OK = qw(parse_log);

sub parse_log {
    my ( $log_file, $pattern ) = @_;
    # parse your log
    # and return something useful                                     
+                                            
}

1;
[download]

What is so difficult with this that you can't figure it out your self?

Karl