Summary

Unix was originally developed at Bell Labs by and for computer scientists. The lack of commercial pressure, combined with the small capacity of the PDP-11 minicomputer, led to a quest for small, elegant programs. The same lack of commercial pressure, though, led to a system that wasn't always consistent, nor easy to learn.

As Unix spread and variant versions developed (notably the System V and BSD variants), portability at the shell script level became difficult. Fortunately, the POSIX standardization effort has borne fruit, and just about all commercial Unix systems and free Unix workalikes are POSIX-compliant.

The Software Tools principles as we've outlined them provide the guidelines for the development and use of the Unix toolset. Thinking with the Software Tools mindset will help you write clear shell programs that make correct use of the Unix tools.

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