anandsunderraman/GNU-Make.md

## GNU-Make.md

      
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              GNU-Make.md
            
          
    GNU Make Cheatsheet

Based on https://www.gnu.org/software/make/manual/html_node/Quick-Reference.html
Directives


Directive
Description


define variable 
 define variable = 
 define variable := 
 define variable ::= 
 define variable += 
 define variable ?= 
 endef
Define multi-line variables.


undefine variable
Undefining variables.


ifdef variable 
 ifndef variable 
 ifeq (a,b) 
 ifeq "a" "b" 
 ifeq 'a' 'b' 
 ifneq (a,b) 
 ifneq "a" "b" 
 ifneq 'a' 'b' 
 else 
 endif
Conditionally evaluate part of the makefile.


include file 
 -include file 
 sinclude file
Include another makefile.


override variable-assignment
Define a variable, overriding any previous definition, even one from the command line.


export
Tell make to export all variables to child processes by default.


export variable 
 export variable-assignment 
 unexport variable
Tell make whether or not to export a particular variable to child processes.


private variable-assignment
Do not allow this variable assignment to be inherited by prerequisites.


vpath pattern path
Specify a search path for files matching a '%' pattern.


vpath pattern
Remove all search paths previously specified for pattern.


vpath
Remove all search paths previously specified in any vpath directive.


Built-in Functions


Function
Description


$(subst from,to,text)
Replace from with to in text.


$(patsubst pattern,replacement,text)
Replace words matching pattern with replacement in text.


$(strip string)
Remove excess whitespace characters from string.


$(findstring find,text)
Locate find in text.


$(filter pattern…,text)
Select words in text that match one of the pattern words.


$(filter-out pattern…,text)
Select words in text that do not match any of the pattern words.


$(sort list)
Sort the words in list lexicographically, removing duplicates.


$(word n,text)
Extract the n-th word (one-origin) of text.


$(words text)
Count the number of words in text.


$(wordlist s,e,text)
Returns the list of words in text from s to e.


$(firstword names…)
Extract the first word of names.


$(lastword names…)
Extract the last word of names.


$(dir names…)
Extract the directory part of each file name.


$(notdir names…)
Extract the non-directory part of each file name.


$(suffix names…)
Extract the suffix (the last '.' and following characters) of each file name.


$(basename names…)
Extract the base name (name without suffix) of each file name.


$(addsuffix suffix,names…)
Append suffix to each word in names.


$(addprefix prefix,names…)
Prepend prefix to each word in names.


$(join list1,list2)
Join two parallel lists of words.


$(wildcard pattern…)
Find file names matching a shell file name pattern (not a '%' pattern).


$(realpath names…)
For each file name in names, expand to an absolute name that does not contain any ., .., nor symlinks.


$(abspath names…)
For each file name in names, expand to an absolute name that does not contain any . or .. components, but preserves symlinks.


$(error text…)
When this function is evaluated, make generates a fatal error with the message text.


$(warning text…)
When this function is evaluated, make generates a warning with the message text.


$(shell command)
Execute a shell command and return its output.


$(origin variable)
Return a string describing how the make variable variable was defined.


$(flavor variable)
Return a string describing the flavor of the make variable variable.


$(foreach var,words,text)
Evaluate text with var bound to each word in words, and concatenate the results.


$(if cond,then-part[,else-part])
Evaluate cond; if it’s non-empty substitute the expansion of the then-part otherwise substitute the expansion of the else-part.


$(or cond1[,cond2[,cond3…]])
Evaluate condN one at a time; substitute the first non-empty expansion. If all expansions are empty, substitute the empty string.


$(and cond1[,cond2[,cond3…]])
Evaluate condN one at a time; if any results in empty string substitute the empty string. Otherwise substitute the expansion of the last condN.


$(call var,param,…)
Evaluate the variable var replacing any references to $(1), $(2) with the first, second, etc. param values.


$(eval text)
Evaluate text then read the results as makefile commands; expands to the empty string.


$(file op filename,text)
Expand the arguments, then open the file filename using mode op and write text to that file.


$(value var)
Evaluates to the contents of the variable var, with no expansion performed on it.


Automatic Variables


Variable
Description


$@
The file name of the target.


$%
The target member name, when the target is an archive member.


$<
The name of the first prerequisite.


$?
The names of all the prerequisites newer than the target, with spaces between them. For prerequisites which are archive members, only the named member is used (see Archives).


$^ 
 $+

The names of all the prerequisites, with spaces between them. For prerequisites which are archive members, only the named member is used (see Archives). The value of $^ omits duplicate prerequisites, while $+ retains them and preserves their order.


$*
The stem with which an implicit rule matches (see How Patterns Match).


$(@D) 
 $(@F)

The directory part and the file-within-directory part of $@.


$(*D) 
 $(*F)

The directory part and the file-within-directory part of $*.


$(%D) 
 $(%F)

The directory part and the file-within-directory part of $%.


$(<D) 
 $(<F)

The directory part and the file-within-directory part of $<.


$(^D) 
 $(^F)

The directory part and the file-within-directory part of $^.


$(+D) 
 $(+F)

The directory part and the file-within-directory part of $+.


$(?D) 
 $(?F)

The directory part and the file-within-directory part of $?.


Special Variables


Variables
Description


MAKEFILES
Makefiles to be read on every invocation of make.


VPATH
Directory search path for files not found in the current directory.


SHELL
The name of the system default command interpreter, usually /bin/sh.


MAKESHELL
The name of the command interpreter that is to be used by make, taking precedence over SHELL (MS-DOS only).


MAKE
The name with which make was invoked (using this variable in recipes has special meaning).


MAKE_VERSION
The built-in variable MAKE_VERSION expands to the version number of the GNU make program.


MAKE_HOST
The built-in variable MAKE_HOST expands to a string representing the host that GNU make was built to run on.


MAKELEVEL
The number of levels of recursion (sub-makes).


MAKEFLAGS
The flags given to make. You can set this in the environment or a makefile to set flags.  It is never appropriate to use MAKEFLAGS directly in a recipe line: its contents may not be quoted correctly for use in the shell. Always allow recursive make’s to obtain these values through the environment from its parent.


GNUMAKEFLAGS
Other flags parsed by make. You can set this in the environment or a makefile to set make command-line flags. GNU make never sets this variable itself. This variable is only needed if you’d like to set GNU make-specific flags in a POSIX-compliant makefile. This variable will be seen by GNU make and ignored by other make implementations. It’s not needed if you only use GNU make; just use MAKEFLAGS directly. See Communicating Options to a Sub-make.


MAKECMDGOALS
The targets given to make on the command line. Setting this variable has no effect on the operation of make.


CURDIR
Set to the absolute pathname of the current working directory (after all -C options are processed, if any). Setting this variable has no effect on the operation of make.


SUFFIXES
The default list of suffixes before make reads any makefiles.


.LIBPATTERNS
Defines the naming of the libraries make searches for, and their order.
Directive	Description
`define variable` `define variable =` `define variable :=` `define variable ::=` `define variable +=` `define variable ?=` `endef`	Define multi-line variables.
`undefine variable`	Undefining variables.
`ifdef variable` `ifndef variable` `ifeq (a,b)` `ifeq "a" "b"` `ifeq 'a' 'b'` `ifneq (a,b)` `ifneq "a" "b"` `ifneq 'a' 'b'` `else` `endif`	Conditionally evaluate part of the makefile.
`include file` `-include file` `sinclude file`	Include another makefile.
`override variable-assignment`	Define a variable, overriding any previous definition, even one from the command line.
`export`	Tell make to export all variables to child processes by default.
`export variable` `export variable-assignment` `unexport variable`	Tell make whether or not to export a particular variable to child processes.
`private variable-assignment`	Do not allow this variable assignment to be inherited by prerequisites.
`vpath pattern path`	Specify a search path for files matching a '%' pattern.
`vpath pattern`	Remove all search paths previously specified for pattern.
`vpath`	Remove all search paths previously specified in any vpath directive.
Function	Description
`$(subst from,to,text)`	Replace `from` with `to` in `text`.
`$(patsubst pattern,replacement,text)`	Replace words matching `pattern` with `replacement` in `text`.
`$(strip string)`	Remove excess whitespace characters from `string`.
`$(findstring find,text)`	Locate find in `text`.
`$(filter pattern…,text)`	Select words in `text` that match one of the `pattern` words.
`$(filter-out pattern…,text)`	Select words in `text` that do not match any of the `pattern` words.
`$(sort list)`	Sort the words in `list` lexicographically, removing duplicates.
`$(word n,text)`	Extract the `n`-th word (one-origin) of `text`.
`$(words text)`	Count the number of words in `text`.
`$(wordlist s,e,text)`	Returns the list of words in `text` from `s` to `e`.
`$(firstword names…)`	Extract the first word of `names`.
`$(lastword names…)`	Extract the last word of `names`.
`$(dir names…)`	Extract the directory part of each file name.
`$(notdir names…)`	Extract the non-directory part of each file name.
`$(suffix names…)`	Extract the suffix (the last '.' and following characters) of each file name.
`$(basename names…)`	Extract the base name (name without suffix) of each file name.
`$(addsuffix suffix,names…)`	Append `suffix` to each word in `names`.
`$(addprefix prefix,names…)`	Prepend `prefix` to each word in `names`.
`$(join list1,list2)`	Join two parallel lists of words.
`$(wildcard pattern…)`	Find file names matching a shell file name pattern (not a '%' pattern).
`$(realpath names…)`	For each file name in `names`, expand to an absolute name that does not contain any ., .., nor symlinks.
`$(abspath names…)`	For each file name in `names`, expand to an absolute name that does not contain any . or .. components, but preserves symlinks.
`$(error text…)`	When this function is evaluated, make generates a fatal error with the message `text`.
`$(warning text…)`	When this function is evaluated, make generates a warning with the message `text`.
`$(shell command)`	Execute a shell command and return its output.
`$(origin variable)`	Return a string describing how the make variable `variable` was defined.
`$(flavor variable)`	Return a string describing the flavor of the make variable `variable`.
`$(foreach var,words,text)`	Evaluate `text` with `var` bound to each word in `words`, and concatenate the results.
`$(if cond,then-part[,else-part])`	Evaluate `cond`; if it’s non-empty substitute the expansion of the `then-part` otherwise substitute the expansion of the `else-part`.
`$(or cond1[,cond2[,cond3…]])`	Evaluate `condN` one at a time; substitute the first non-empty expansion. If all expansions are empty, substitute the empty string.
`$(and cond1[,cond2[,cond3…]])`	Evaluate `condN` one at a time; if any results in empty string substitute the empty string. Otherwise substitute the expansion of the last `condN`.
`$(call var,param,…)`	Evaluate the variable `var` replacing any references to `$(1)`, `$(2)` with the first, second, etc. param values.
`$(eval text)`	Evaluate `text` then read the results as makefile commands; expands to the empty string.
`$(file op filename,text)`	Expand the arguments, then open the file `filename` using mode `op` and write `text` to that file.
`$(value var)`	Evaluates to the contents of the variable `var`, with no expansion performed on it.
Variable	Description
`$@`	The file name of the target.
`$%`	The target member name, when the target is an archive member.
`$<`	The name of the first prerequisite.
`$?`	The names of all the prerequisites newer than the target, with spaces between them. For prerequisites which are archive members, only the named member is used (see Archives).
`$^` `$+`	The names of all the prerequisites, with spaces between them. For prerequisites which are archive members, only the named member is used (see Archives). The value of $^ omits duplicate prerequisites, while $+ retains them and preserves their order.
`$*`	The stem with which an implicit rule matches (see How Patterns Match).
`$(@D)` `$(@F)`	The directory part and the file-within-directory part of `$@`.
`$(D)` `$(F)`	The directory part and the file-within-directory part of `$*`.
`$(%D)` `$(%F)`	The directory part and the file-within-directory part of `$%`.
`$(<D)` `$(<F)`	The directory part and the file-within-directory part of `$<`.
`$(^D)` `$(^F)`	The directory part and the file-within-directory part of `$^`.
`$(+D)` `$(+F)`	The directory part and the file-within-directory part of `$+`.
`$(?D)` `$(?F)`	The directory part and the file-within-directory part of `$?`.
Variables	Description
`MAKEFILES`	Makefiles to be read on every invocation of make.
`VPATH`	Directory search path for files not found in the current directory.
`SHELL`	The name of the system default command interpreter, usually `/bin/sh`.
`MAKESHELL`	The name of the command interpreter that is to be used by make, taking precedence over `SHELL` (MS-DOS only).
`MAKE`	The name with which make was invoked (using this variable in recipes has special meaning).
`MAKE_VERSION`	The built-in variable `MAKE_VERSION` expands to the version number of the GNU make program.
`MAKE_HOST`	The built-in variable `MAKE_HOST` expands to a string representing the host that GNU make was built to run on.
`MAKELEVEL`	The number of levels of recursion (sub-makes).
`MAKEFLAGS`	The flags given to make. You can set this in the environment or a makefile to set flags. It is never appropriate to use MAKEFLAGS directly in a recipe line: its contents may not be quoted correctly for use in the shell. Always allow recursive make’s to obtain these values through the environment from its parent.
`GNUMAKEFLAGS`	Other flags parsed by make. You can set this in the environment or a makefile to set make command-line flags. GNU make never sets this variable itself. This variable is only needed if you’d like to set GNU make-specific flags in a POSIX-compliant makefile. This variable will be seen by GNU make and ignored by other make implementations. It’s not needed if you only use GNU make; just use MAKEFLAGS directly. See Communicating Options to a Sub-make.
`MAKECMDGOALS`	The targets given to make on the command line. Setting this variable has no effect on the operation of make.
`CURDIR`	Set to the absolute pathname of the current working directory (after all -C options are processed, if any). Setting this variable has no effect on the operation of make.
`SUFFIXES`	The default list of suffixes before make reads any makefiles.
`.LIBPATTERNS`	Defines the naming of the libraries make searches for, and their order.