Add this feature to the function you wrote for exercise 14.

The Linux basename utility has an optional second argument. If you give
the command basename path suffix, basename removes the suffix and the
prefix from path:
$ basename src/shellfiles/prog.bash .bash
prog
$ basename src/shellfiles/prog.bash .c
prog.bash

$ function bn2 () {
> if [ $# = 0 ]; then
> exit 1
> elif [ "$1" = "/" ]; then
> echo /
> else
> ans=$(echo $1 | sed 's:.*/::')
> if [ $# = 2 ]; then
> echo $ans | sed "s:\(.*\)$2$:\1:"
> else echo $ans
> fi
> fi
> }