GNUMake Cheat Sheet

A Software › Linux cheat sheet in English by bavo.van.achte

Cheat sheet with commonly used constructions in Makefiles based on GNU Make

29,751 views 9,432 downloads 22 Oct 2014 History

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Make command line options

target	Select the target to run
-f file	Select which file to read
-W file	Mark file as 'out of date'
-C	Change directory before making
-d	Print all debug information
-n	Print actions without making
-t	Mark encountered targets as 'up of date'
-p	Expand makefile and print
-b	Consider all targets as 'out-of-date'

Automatic variables

$@	Name of the target of the recipe being run*
$%	The target member name, when the target is an archive member*
$<	Name of first prerequisite
$?	Names of prerequisites newer than the target
$^	Names of all prerequisites
$*	Name of the stem

* In case of foo.a(bar.o) $@ returns "foo.a" and $% returns "bar.o"

.PHONY

Certain targets can be marked as .PHONY. By doing this, you notify make that the target is not related to a specific filename. It will thus always be rebuilt.

.PHONY: clean
clean:
 rm *.o temp

In the example given, clean will always be rebuilt, even if a file named "clean" is found

Text manipulation functions

Syntax: $(function arguments)
$(subst from,to,text)
	Substitute substring from to to in text
$(patsubst pat,repl,text)
	Text substitutions using pattern pat in text
$(text:pat=repl)
	Same effect as patsubst, but in different form
$(strip string)
	Strip leading and trailing spaces from string
$(findstring find,strings)
	Tries to find occurence of find in strings. Returns 'find' if successful, else it returns ''
$(filter patterns,text)
	Returns words in text that match patterns
$(filter-out pattern...,text)
	Returns words in text that DO NOT match patterns
$(sort list)
	Sort list list of strings in alfabetical order
$(word n,text)
	Return the n^th word in text
$(wordlist s,e,text)
	Return sublist of words list text starting at index s and ending at index e
$(words text)
	Returns the number of words in text
$(firstword text)
	Returns the first word in text
$(lastword text)
	Returns the last word in text

General rule syntax

In general, a rule looks like this:
targets : prerequisites
recipe
...
or like this:
targets : prerequisites ; recipe
recipe
...

Variable assignment

Recursively expanded variable
var = $(shell ls)
The expansion of $(shell ls) only happens when var is referenced

Simply expanded variable
var := $(shell ls)
var ::= $(shell ls)
The expansion of $(shell ls) is done immediately

Conditionally expanded variable
var ?= $(shell ls)
Assigns the variable recursively if it is not yet defined

Incremental assignment
var += $(shell ls)
Appends to the variable. Assignment (recursive/simple) depends on var

Shell assignment
var != ls
Executes the ls command immediately in the shell and assigns result to var

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Comments (1)

arvindms82 08:41 10 Apr 2019

useful