Short Notes on Bash
From PaskvilWiki
Extensions and File Name
$ fullname='/tmp/file.tar.gz'
$ filename=$(basename $fullname)
$ echo ${filename##*.}
>> gz
$ echo ${filename#*.}
>> tar.gz
$ echo ${filename%.*}
>> file.tar
$ echo ${filename%%.*}
>> file
For more options and explanations, see Bash - Shell Parameters Expansion.