How to get extension of file in perl, PHP,BASH etc

How to get a file extension
How to get a file extension in PHP:

$ext = pathinfo($file_name, PATHINFO_EXTENSION);
How to get a file extension in Perl:

my $ext = ($file_name =~ m/([^.]+)$/)[0];
How to get a file extension in Ruby:

ext = File.extname(file_name)
How to get a file extension in Bash:

ext=${file_name##*.}
name=${file_name%.*}
How to get a file extension in Python:

import os
ext = os.path.splitext(file_name)[1]