Almquist shell

The Almquist shell (also known as A Shell, ash and sh) is a lightweight Unix shell originally written by Kenneth Almquist in the late 1980s. Initially a clone of the System V.4 variant of the Bourne shell, it replaced the original Bourne shell in the BSD versions of Unix released in the early 1990s. Derivative versions of ash are still installed as the default shell (/bin/sh) on FreeBSD, NetBSD, DragonFly BSD, MINIX, and Android, and in some Linux distributions.