Dollar-sign expansions are definitions of text replacements used in the script or in expressions. This process is known as expansion - even if the new text is shorter. The replacement is made just before the script statement or the expression is evaluated. Technically it is a macro expansion.
The expansion always begins with '$(' and ends with ') ' and the content between brackets defines how the text replacement will be done. To avoid confusion with script macros we will henceforth refer to macro expansions as dollar-sign expansions.
Dollar-sign expansions can be used with either of:
- variables
- parameters
- expressions
Note: A dollar-sign expansion is limited in how many expansions it can calculate. Any expansion with over 1000 levels of nested expansions will not be calculated.