Avoid calling basename or dirname by using parameter expansion

These short cuts have been documented under parameter expansion for a long time but are not well known because people are used to writing basename and dirname.

Instead of using:

file=$(basename "$path")

use

file=${path##*/}

Instead of using:

dir=$(dirname "$path")

use

dir=${path%/*}

The advantage is not calling basename as an extra process. Although basename might be implemented as a builtin in some shells.

See the linked page for further short cuts.