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5.6.1 How the MAKE Variable Works

Recursive make commands should always use the variable MAKE, not the explicit command name `make', as shown here:

 
subsystem:
        cd subdir && $(MAKE)

The value of this variable is the file name with which make was invoked. If this file name was `/bin/make', then the command executed is `cd subdir && /bin/make'. If you use a special version of make to run the top-level makefile, the same special version will be executed for recursive invocations.

As a special feature, using the variable MAKE in the commands of a rule alters the effects of the `-t' (`--touch'), `-n' (`--just-print'), or `-q' (`--question') option. Using the MAKE variable has the same effect as using a `+' character at the beginning of the command line. See section Instead of Executing the Commands.

Consider the command `make -t' in the above example. (The `-t' option marks targets as up to date without actually running any commands; see 9.3 Instead of Executing the Commands.) Following the usual definition of `-t', a `make -t' command in the example would create a file named `subsystem' and do nothing else. What you really want it to do is run `cd subdir && make -t'; but that would require executing the command, and `-t' says not to execute commands.

The special feature makes this do what you want: whenever a command line of a rule contains the variable MAKE, the flags `-t', `-n' and `-q' do not apply to that line. Command lines containing MAKE are executed normally despite the presence of a flag that causes most commands not to be run. The usual MAKEFLAGS mechanism passes the flags to the sub-make (see section Communicating Options to a Sub-make), so your request to touch the files, or print the commands, is propagated to the subsystem.


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