basename example.tar.gz .tar.gz
# => example
FILE=example.tar.gz
echo ${FILE%%.*}
# => example
echo ${FILE%.*}
# => example.tar
echo ${FILE#*.}
# => tar.gz
echo ${FILE##*.}
# => gz
# 在bash中可以这么写
filename=$(basename $fullfile)
extension=${filename##*.}
filename=${filename%.*}