my $file_name = ( split m{/}, $0 )[-1];

##</code><code>##

my $file_name = substr $0, 1 + rindex $file, '/';

##</code><code>##

my ( $file_name ) = $0 =~ m{([^/]+)$};

##</code><code>##

use File::Basename qw(basename);

my $file_name = basename $0;