X Window Programming from Scratch

Appendix A. Command Shells and Scripting

The UNIX command shell is adequately named because what is visible is only the outside. Internally, there is much more to a command shell than is immediately understood.

UNIX is unique in letting users choose their command shell. Most operating systems (DOS, VMS, and so forth) have the command interpreter built in, giving users no alternative.

Under UNIX, the command interpreter is not a part of the operating system but rather a wrapper around it.

This appendix provides an overview of the command shells commonly available under many UNIX systems. Following an overview of shells, the focus is on writing shell scripts using the Bourne shell.

UNIX Command Shells

The Bourne shell (sh) is the standard among ...