Running external command after saving file

[juman]

I have a small shell script that creates snapshots of files and I want
to add it to be runned by Emacs when saving a file. Could anybody give
me a hint how I could to that?

So what I want is to add a command to emacs to use instead of C-s that
would save the current buffer and then run the specified command on that
file.

/juman