Removing everything but filename extension [duplicate]

Question

Let's say I have a string:

x=file.tar.sh

I know how to remove everything but last n-characters. Like this (removing everything but last 3 characters:

${x: -3}

But this doesn't work for files with different suffix lengths. (len .tar != len .sh)

I would tackle this by removing everything until the last dot. I've tried this:

${x##.}

This removes the longest matching until "." but somehow it just returns the full string without removing anything?

Answer 1

Try this:

x=file.tar.sh
echo ${x##*.}

This will print sh

If you want to get tar.sh, then:

echo ${x#*.}

Here * matches any set of characters before the occurrence of .