Summary
In this chapter, we have written two useful tools that do not already exist on Unix systems, using shell statements and existing standard tools to carry out the task. Neither of them is particularly time-consuming to run, so there is little temptation to rewrite them in a programming language like C or C++. As shell scripts, they can be run without change on almost any modern Unix platform.
Both programs support command-line options, cleanly processed by while and case statements. Both use shell functions to simplify processing and prevent unnecessary code duplication. Both pay attention to security issues and perform sanity checks on their arguments and variables.
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