md5-hash.sh

#!/bin/bash
#
# Calculates the MD5 hash of a given file. It uses hashing utilities powered by
# operating systems, but wraps them into a consistent interface.

OS=$(
    case $(uname) in
        (Darwin*)  echo "mac";;
        (Linux*)   echo "linux";;
        # TODO: implement MD5 hashing on Windows
        # (Windows*) echo "windows";;
        (*)        echo "linux";;
    esac
)

case $OS in
    mac )
        md5 -q $1;;
    linux )
        echo md5sum $1 | sed -E 's/([a-z0-9]{32}).+$/\1/';;
esac