Learning about Variable Arrays

A really cool feature of environment variables is that they can be used as arrays. An array is a variable that can hold multiple values. Values can be referenced either individually or as a whole for the entire array.

To set multiple values for an environment variable, just list them in parentheses, with values separated by spaces:

$ mytest=(one two three four five)
$

Not much excitement there. If you try to display the array as a normal environment variable, you'll be disappointed:

$ echo $mytest
one
$

Only the first value in the array appears. To reference an individual array element, you must use a numerical index value, which represents its place in the array. The numeric value is enclosed in square brackets:

$ echo ${mytest[2]}
three
$

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Tip

Environment variable arrays start with an index value of zero. This can be confusing.

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To display an entire array variable, you use the asterisk wildcard character as the index value:

$ echo ${mytest[*]...