A command macro is a text file that contains one or more commands and/or command macro statements and that has a name ending with the suffix .cm. You invoke a macro by entering its name. The operating system then sequentially executes the commands and macro statements in the file. A command macro is useful to replace one of the following: a long command string that you issue frequently a group of internal commands, command macros, and/or program modules that together perform an operation you regularly require a sequence of internal commands, command macros, and/or program modules that you execute in a certain way depending on external factors