5 - Now That's Leverage!

Abstract

This chapter is designed to study tenet six of the Unix philosophy—using software leverage to ones advantage. It explores some principles concerning the use of leverage. One reason for the success of Unix is its ability to aid the leveraging efforts of individuals. It came about by way of cooperative design by hundreds of programmers. They realized that if they could multiply their effects, they could take advantage of software leverage. The best way to write lots of software is to borrow it. Borrowing software means incorporating other people's modules, programs, and configuration files into ones applications. Unix owes much of its success to the fact that its developers saw no particular need to retain strong control of its source code. The use of software leverage through increased automation can result in huge productivity gains. Another important element of Unix is the shell script. Shell scripts capitalize on software leverage in interesting ways. They make it easy for users to tap into the incredible potential found in Unix. Experienced Unix programmers use them religiously. Shell scripts bear some resemblance to other command interpreters and control mechanisms, such as batch files under MS-DOS and DCL command files under OpenVMS. Unlike these other implementations, however, Unix shell scripts exist in an environment ideally suited for indirect command execution.