The for loop

The for loop can be considered the more powerful loop in Bash scripting. In practice, for and while are interchangeable, but for has better shorthand syntax. This means that to write a loop in for often requires much less code than an equivalent while loop.

The for loop has two different syntaxes: a C-style syntax and the regular Bash syntax. We'll first look at the Bash syntax:

FOR value IN list-of-values DO thing-with-value DONE

A for loop allows us to iterate over a list of things. Each loop will use a different item in that list, in a sequential order. This very simple example should illustrate this behavior:

reader@ubuntu:~/scripts/chapter_11$ vim for-simple.sh
reader@ubuntu:~/scripts/chapter_11$ cat for-simple.sh 
#!/bin/bash

#####################################
# Author: Sebastiaan Tammer
# Version: v1.0.0
# Date: 2018-10-27
# Description: Simple for syntax.
# Usage: ./for-simple.sh
#####################################

# Create a 'list'.
words="house dog telephone dog...