$ pwd
/home/aitap
$ cat /tmp/1.pl
#!/usr/bin/perl
use strict;
use warnings;
use Cwd;

my $script_dirname = cwd;
print "dirname: $script_dirname\n";

use Cwd 'abs_path';
use File::Basename;
$script_dirname = dirname(abs_path($0));
print "script dirname: $script_dirname\n";
$ perl /tmp/1.pl 
dirname: /home/aitap
script dirname: /tmp