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3 Expansion

Expansion in a command shell is somewhat like macro expansion in macro parsers (such as cpp and m4), but in a command shell, they are less often used for constants, and usually for using variables and string manipulation.6 For example, $var on a line expands to the value of the variable var when the line is executed. Expansions are usually passed as arguments, but may also be used as commands.7



Eshell has no string-manipulation expansions because the Elisp library already provides many functions for this.


E.g., entering just ‘$var’ at the prompt is equivalent to entering the value of var at the prompt.