Because a typical shell script calls so many different commands, knowing the commands provided to you by the Bash shell itself, and by the system on which it runs, equips you to choose the right tool for the job; that decision can be particularly difficult in shell scripting, with so many options and alternatives available.
Knowing what the Bash shell provides – and what the POSIX standard specifies for the system to provide – will help you write shell scripts that will run safely, reliably, and portably on the systems where you need them to run. Tools like type, help, and man will enable you to identify and find the correct documentation for these commands.
In the next chapter, we'll look at how we can specify and redirect input and output for these and other commands, allowing you to pass just the data you need to them, just when you need it.
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