Make- GNU Project Free Software Foundation

There may also be prerequisites that do not use ‘%’; such a prerequisite attaches to every file made by this pattern rule. These unvarying prerequisites are useful occasionally. You can explicitly mark a file as intermediate by listing it as a prerequisite of the special target .INTERMEDIATE. This takes effect even if the file is mentioned explicitly in some other way. The second difference is that if make does create b in order to update something else, it deletes b later on after it is no longer needed. Therefore, an intermediate file which did not exist beforemake also does not exist after make.


On MS-DOS, the value of current working directory is global, so changing it will affect the following recipe lines on those systems. Some older versions of GNU make did not sort the results of wildcard expansion. You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by any one entity. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies.

Appendix D GNU Free Documentation License

$(?D)$(?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 $%.

More generally, ‘make maintainer-clean’ should not delete anything that needs to exist in order to run configure and then begin to build the program. Also, there is no need to delete parent directories that were created with ‘mkdir -p’, since they could have existed anyway. These are the only exceptions;maintainer-clean should delete everything else that can be rebuilt. ‘distclean’Delete all files in the current directory that are created by configuring or building the program.

Then for each word of the expanded value of list, the variable named by the expanded value of varis set to that word, and text is expanded. Presumably textcontains references to that variable, so its expansion will be different each time. This includes variables which have empty values, as well as built-in variables , but does not include any variables which are only defined in a target-specific context. Note that any value you assign to this variable will be ignored; it will always return its special value. In this example the first definition of the CFLAGS variable will be used to update lib/bar.o even though the second one also applies to this target.

  • Results in the OUT variable containing the text ‘one$$two’.
  • Now the rule to create the objdir directory will be run, if needed, before any ‘.o’ is built, but no ‘.o’ will be built because the objdir directory timestamp changed.
  • N is made automatically from n.o by running the C compiler to link the program.
  • It is ok to use other utilities in Makefile portions intended only for particular systems where you know those utilities exist.

Thus, any reference to $ in the value of variable will resolve to the first param in the invocation of call. When writing files, text will be written to the file. Iftext does not already end in a newline a final newline will be written . If the textargument is not given at all, nothing will be written. When reading files, it is an error to provide a text value. The let function provides a means to limit the scope of a variable.

This class of language, in which necessary end conditions are described but the order in which actions are to be taken is not important, is sometimes confusing to programmers used to imperative programming. With SunOS-3.2, It was delivered as optional program; with SunOS-4.0, SunPro Make was made the default Make program. In December 2006, Sun DevPro Make was made open source as part of the efforts to open-source Solaris.

10 Variables from the Environment

If var was undefined before the foreachfunction call, it is undefined after the call. Several of the built-in expansion functions relate specifically to taking apart file names or lists of file names. When using characters that are special to make as function arguments, you may need to hide them. GNU make doesn’t support escaping characters with backslashes or other escape sequences; however, because arguments are split before they are expanded you can hide them by putting them into variables. Be aware that a given prerequisite will only be built once per invocation of make, at most.

If you want that file to be built, you will need to add a rule to your makefile describing how that target can be built. Other possible sources of this problem are typos in the makefile or a corrupted source tree . In this case, make will use the second form of the error above.

If a recipe fails , and errors are not ignored for that recipe , the remaining recipe lines to remake the same target will not be run. If a recipe fails and the ‘-k’ or ‘–keep-going’ option was not given , make aborts execution. If make terminates for any reason with child processes running, it waits for them to finish before actually exiting. GNU make knows how to execute several recipes at once. Normally,make will execute only one recipe at a time, waiting for it to finish before executing the next.

That is, the target and prerequisite sections are expanded immediately, and the recipe used to build the target is always deferred. This is true for explicit rules, pattern rules, suffix rules, static pattern rules, and simple prerequisite definitions. Before recompiling an object file, make considers updating its prerequisites, the source file and header files. This makefile does not specify anything to be done for them—the ‘.c’ and ‘.h’ files are not the targets of any rules—so make does nothing for these files. But make would update automatically generated C programs, such as those made by Bison or Yacc, by their own rules at this time. Stop.’These errors are generated for malformed static pattern rules .

With the type ‘none’, no output synchronization is performed. Specifies that no new recipes should be started if there are other recipes running and the load average is at least load (a floating-point number). In some situations, make will need to create its own temporary files. These files must not be disturbed while make is running, including all recursively-invoked instances of make. The usual behavior of make assumes that your purpose is to get the goals up to date; once make learns that this is impossible, it might as well report the failure immediately.

Functions for Transforming Text

Which tells how to make ‘.o’ files from ‘.c’ files, and makes all ‘.o’ files using this pattern rule also depend on foo.h. If you do not want a target to get the recipe from a match-anything pattern rule or .DEFAULT, but you also do not want any recipe to be run for the target, you can give it an empty recipe . We know these possibilities are ridiculous since foo.c is a C source file, not an executable.


It does so because one of the commands in the recipe is a touchcommand to update the target file. If a rule has no prerequisites or recipe, and the target of the rule is a nonexistent file, then imagines this target to have been updated whenever its rule is run. This implies that all targets depending on this one will always have their recipe run. The search through the directories specified in VPATH or withvpath also happens during consideration of implicit rules .

If the target is an archive member, then ‘$@’ is the name of the archive file. In a pattern rule that has multiple targets , ‘$@’ is the name of whichever target caused the rule’s recipe to be run. If you do not want make to create a file merely because it does not already exist, but you also do not want make to automatically delete the file, you can mark it as a secondaryfile. To do this, list it as a prerequisite of the special target.SECONDARY. Marking a file as secondary also marks it as intermediate. Because you mention foo.o but do not give a rule for it, makewill automatically look for an implicit rule that tells how to update it.

Using make to Update Archive Files

The ‘-e’ flag tells the shell to exit as soon as any program it runs returns a nonzero status. We feel it is cleaner to write each line of the recipe to stand on its own and not require this special treatment. Use a special search method for library prerequisites written in the form ‘-lname’. The automatic variable $% is set to the member name in an archive reference. The –output-sync option will defeat the terminal detection. When output synchronization is enabled GNU make arranges for all command output to be written to a file, so that its output can be written as a block without interference from other commands.

If expanding a variable has side-effects then these side-effects will be seen every time a command is invoked. You can avoid this by ensuring that such variables have names which are not exportable by default. However, a better solution is tonot use this “export by default” facility at all, and instead explicitly export the relevant variables by name. Make automatically passes down variable values that were defined on the command line, by putting them in the MAKEFLAGS variable. Some programs invoked by make may behave differently if they determine they’re writing output to a terminal versus a file (often described as “interactive” vs. “non-interactive” modes). For example, many programs that can display colorized output will not do so if they determine they are not writing to a terminal.

Pattern-specific variables which result in the same stem length are considered in the order in which they were defined in the makefile. As with target-specific variable values, multiple pattern values create a pattern-specific variable value for each pattern individually. The variable-assignment can be any valid form of assignment. Any command line variable setting will take precedence, unless override is specified.

‘install’Compile the program and copy the executables, libraries, and so on to the file names where they should reside for actual use. If there is a simple test to verify that a program is properly installed, this target should run that test. By default, the What is MAKE rules should compile and link with ‘-g’, so that executable programs have debugging symbols.

Returning too few slots means that those slots will be lost for the rest of the build process; returning too many slots means that extra slots will be available. The top-level make command will print an error message at the end of the build if it detects an incorrect number of slots available in the jobserver. GNU make has the ability to run multiple recipes in parallel and to cap the total number of parallel jobs even across recursive invocations of make(see Communicating Options to a Sub-make). FlagsFlags that specify how this function will operate; the desired flags should be OR’d together. If the GMK_FUNC_NOEXPAND flag is given then the function arguments will not be expanded before the function is called; otherwise they will be expanded first. This is what the makefile should use to invoke the function.

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