How to install?
Create new file

nano /usr/bin/md5

copy&paste code to /usr/bin/md5

chmod:

chmod +x /usr/bin/md5

Code:

#!/bin/sh
if [ $1 ]
then
        hash="$(echo -n "$1" | md5sum )"
        echo "$hash"
else
        echo "Example usage: md5 <you-string>"
fi

Usage and Output:

root@host:~# md5 sebastian
c2d628ba98ed491776c9335e988e2e3b  &#8211;