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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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