There used to be a time when being a system programmer bought some respect, even if the system programmer was kept in a glass room. Well, Unix has changed all that. Anyone can system program. In fact, shell programs (or scripts, exec's, command files, run files) are powerful and simple techniques which saves much time and aggravation.
A shell program or shell script is an ordinary text file containing commands which will eventually be read by the shell. The script is written for any of the Unix shells you have available, with most users using sh or ksh since these shells provide a simple and easy-to-use programming language. The Korn shell is a superset of the older Borne shell, so you may start by writing your scripts for the simpler Borne shell and incorporate Korn shell features as you need them. The C shell provides a very flexible programming syntax, but it is also rather cumbersome. We present the basics of programming in the Borne shell with some Korn shell enhancements.