How do you force a makefile to rebuild a target?

Lodle_23339 0
Viewed 246820

I have a makefile that builds and then calls another makefile. Since this makefile calls more makefiles that does the work it doesn't really change. Thus it keeps thinking the project is built and up to date.

dnetdev11 ~ # make
make: `release' is up to date.

How do I force the makefile to rebuild the target?

clean = $(MAKE) -f ~/xxx/xxx_compile.workspace.mak clean


build = svn up ~/xxx                                                       \
        $(clean)                                                                \
        ~/cbp2mak/cbp2mak -C ~/xxx ~/xxx/xxx_compile.workspace        \
        $(MAKE) -f ~/xxx/xxx_compile.workspace.mak $(1)                    \


release:
        $(build )

debug:
        $(build DEBUG=1)

clean:
        $(clean)

install:
        cp ~/xxx/source/xxx_utility/release/xxx_util /usr/local/bin
        cp ~/xxx/source/xxx_utility/release/xxxcore.so /usr/local/lib

Note: Names removed to protect the innocent

Final Fixed version:

clean = $(MAKE) -f xxx_compile.workspace.mak clean;


build = svn up;                                         \
        $(clean)                                        \
        ./cbp2mak/cbp2mak -C . xxx_compile.workspace;   \
        $(MAKE) -f xxx_compile.workspace.mak    $(1);   \


.PHONY: release debug clean install

release:
        $(call build,)

debug:
        $(call build,DEBUG=1)

clean:
        $(clean)

install:
        cp ./source/xxx_utillity/release/xxx_util /usr/bin
        cp ./dlls/Release/xxxcore.so /usr/lib
makefile linux
15 Answers

The -B switch to make, whose long form is --always-make, tells make to disregard timestamps and make the specified targets. This may defeat the purpose of using make, but it may be what you need.

sykora_538500

You could declare one or more of your targets to be phony.

A phony target is one that is not really the name of a file; rather it is just a name for a recipe to be executed when you make an explicit request. There are two reasons to use a phony target: to avoid a conflict with a file of the same name, and to improve performance.

...

A phony target should not be a prerequisite of a real target file; if it is, its recipe will be run every time make goes to update that file. As long as a phony target is never a prerequisite of a real target, the phony target recipe will be executed only when the phony target is a specified goal

Dave_277310

One trick that used to be documented in a Sun manual for make is to use a (non-existent) target '.FORCE'. You could do this by creating a file, force.mk, that contains:

.FORCE:
$(FORCE_DEPS): .FORCE

Then, assuming your existing makefile is called makefile, you could run:

make FORCE_DEPS=release -f force.mk -f makefile release

Since .FORCE does not exist, anything that depends on it will be out of date and rebuilt.

All this will work with any version of make; on Linux, you have GNU Make and can therefore use the .PHONY target as discussed.

It is also worth considering why make considers release to be up to date. This could be because you have a touch release command in amongst the commands executed; it could be because there is a file or directory called 'release' that exists and has no dependencies and so is up to date. Then there's the actual reason...

user_151680

Someone else suggested .PHONY which is definitely correct. .PHONY should be used for any rule for which a date comparison between the input and the output is invalid. Since you don't have any targets of the form output: input you should use .PHONY for ALL of them!

All that said, you probably should define some variables at the top of your makefile for the various filenames, and define real make rules that have both input and output sections so you can use the benefits of make, namely that you'll only actually compile things that are necessary to copmile!

Edit: added example. Untested, but this is how you do .PHONY

.PHONY: clean    
clean:
    $(clean)
user_167060

If I recall correctly, 'make' uses timestamps (file modification time) to determine whether or not a target is up to date. A common way to force a re-build is to update that timestamp, using the 'touch' command. You could try invoking 'touch' in your makefile to update the timestamp of one of the targets (perhaps one of those sub-makefiles), which might force Make to execute that command.

user_37880

As abernier pointed out, there is a recommended solution in the GNU make manual, which uses a 'fake' target to force rebuilding of a target:

clean: FORCE
        rm $(objects)
FORCE: ;

This will run clean, regardless of any other dependencies.

I added the semicolon to the solution from the manual, otherwise an empty line is required.

user_74577500
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