Sometimes you need a Makefile to be able to run on different target OS’s and you want the build to fail early if a required executable is not in PATH rather than to run for a possibly long time before failing. The excellent solution provided by engineerchuan requires making a target. However, if you have … Read more
CPPFLAGS is supposed to be for flags for the C PreProcessor; CXXFLAGS is for flags for the C++ compiler. The default rules in make (on my machine, at any rate) pass CPPFLAGS to just about everything, CFLAGS is only passed when compiling and linking C, and CXXFLAGS is only passed when compiling and linking C++.
I’m not really too clear what you are asking, but using the -f command line option just specifies a file – it doesn’t tell make to change directories. If you want to do the work in another directory, you need to cd to the directory: clean: cd gtest-1.4.0 && $(MAKE) clean Note that each line … Read more
Simple assignment := A simple assignment expression is evaluated only once, at the very first occurrence. For example, if CC :=${GCC} ${FLAGS} during the first encounter is evaluated to gcc -W then each time ${CC} occurs it will be replaced with gcc -W. Recursive assignment = A Recursive assignment expression is evaluated everytime the variable … Read more
You can use Target-specific Variable Values. Example: CXXFLAGS = -g3 -gdwarf2 CCFLAGS = -g3 -gdwarf2 all: executable debug: CXXFLAGS += -DDEBUG -g debug: CCFLAGS += -DDEBUG -g debug: executable executable: CommandParser.tab.o CommandParser.yy.o Command.o $(CXX) -o output CommandParser.yy.o CommandParser.tab.o Command.o -lfl CommandParser.yy.o: CommandParser.l flex -o CommandParser.yy.c CommandParser.l $(CC) -c CommandParser.yy.c Remember to use $(CXX) or $(CC) … Read more
It means “don’t echo this command on the output.” So this rule is saying “execute the shell command : and don’t echo the output. Of course the shell command : is a no-op, so this is saying “do nothing, and don’t tell.” Why? The trick here is that you’ve got an obscure combination of two … Read more
They control the behaviour of make for the tagged command lines: @ suppresses the normal ‘echo’ of the command that is executed. – means ignore the exit status of the command that is executed (normally, a non-zero exit status would stop that part of the build). + means ‘execute this command under make -n‘ (or … Read more
In your example, the TMP variable is set (and the temporary directory created) whenever the rules for out.tar are evaluated. In order to create the directory only when out.tar is actually fired, you need to move the directory creation down into the steps: out.tar : $(eval TMP := $(shell mktemp -d)) @echo hi $(TMP)/hi.txt tar … Read more
The shell function. You can use shell function: current_dir = $(shell pwd). Or shell in combination with notdir, if you need not absolute path: current_dir = $(notdir $(shell pwd)). Update. Given solution only works when you are running make from the Makefile’s current directory. As @Flimm noted: Note that this returns the current working directory, … Read more
Under Bash (at least), this can be done automatically with tab completion: make spacetabtab