Programming Utilities Guide

Summary of Built-In `m4` Macros

Table 6-1 Summary of Built-In m4 Macros


Built-In m4 Macros	Description
`changequote(L, R)`	Change left quote to `L`, right quote to `R`.
`changecom`	Change left and right comment markers from the default # and newline.
`decr`	Return the value of the argument decremented by 1.
`define(name, stuff)`	Define `name` as `stuff`.
defn(`name')	Return the quoted definition of the argument(s)
`divert(number)`	Divert output to stream `number`
`divnum`	Return number of currently active diversions
`dnl`	Delete up to and including newline
dumpdef(`name', `name', . . .)	Dump specified definitions.
`errprint(s, s, . . .)`	Write arguments `s` to standard error.
`eval(numeric expression)`	Evaluate `numeric expression`.
ifdef(`name', true string, false string)	Return `true string` if name is defined, `false string` if name is not defined.
`ifelse(a, b, c, d)`	If `a` and `b` are equal, return `c`, else return `d`.
`include(file)`	Include contents of file.
`incr(number)`	Increment number by 1.
`index(s1, s2)`	Return position in `s1` where `s2` occurs, or -1 if `s2` does not work.
`len(string)`	Return length of `string`.
`maketemp(. . .XXXXX. . .)`	Make a temporary file.
`m4 exit`	Cause immediate `exit` from `m4`.
`m4 wrap`	Argument 1 will be returned to the input stream at final `EOF`.
`popdef`	Remove current definition of argument(s).
`pushdef`	Save any previous definition (similar to `define()`)
`shift`	Return all but first argument(s)
`sinclude(file)`	Include contents of file -- ignore and continue if file not found
`substr(string, position, number)`	Return substring of `string` starting at `position` and `number` characters long
`syscmd(command)`	Run command in the system
`sysval`	Return code from the last call to `syscmd()`
`traceoff`	Turn off trace globally and for any macros specified
`traceon`	Turn on tracing for all macros, or with arguments, turn on tracing for named macros
`translit(string, from, to)`	Transliterate characters in `string` from the set specified by `from` to the set specified by `to`
undefine(`name')	Remove name from the list of definitions
`undivert(number, number,. . .)`	Append diversion number to the current diversion

Summary of Built-In m4 Macros

Summary of Built-In `m4` Macros