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 (thanks to Jensen):

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

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