In this final chapter on flow control, we will look at another of the shell’s looping constructs. The for loop differs from the while and until loops in that it provides a means of processing sequences during a loop. This turns out to be very useful when programming. Accordingly, the for loop is a popular construct in bash scripting.

A for loop is implemented, naturally enough, with the for compound command. In bash, for is available in two forms.

for: Traditional Shell Form

The original for command’s syntax is as follows:

for variable [in words]; do      commandsdone

where variable is the name of a variable that ...

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