There are almost 60 built-in commands and more than 20 reserved words in bash. Some of them are indispensable, and some are rarely used in scripts. Some are used primarily at the command line, and some are seldom seen anywhere. Some have been discussed already, and others will be used extensively in future chapters.
The reserved words (also called keywords) are !, case, coproc, do, done, elif, else, esac, fi, for, function, if, in, select, then, until, while, {, }, time, [[, and ]]. All except coproc, select, and ...
