My Makefile contains something like
BASE_VAR=$(cat path/to/value.txt)
DERIVED_VAR=$(if $(BASE_VAR),foo,bar)
This does not produce the results I expected. make --debug=a produces detailed trace but path/to/value.txt doesn't appear anywhere in it. How do I debug this kind of variable assignment in a makefile?
The problem comes from:
BASE_VAR=$(cat path/to/value.txt)
As there is not make variable or macro named cat path/to/value.txt the expansion
$(cat path/to/value.txt) produces the empty string. If you want to set variable BASE_VAR with the content of file path/to/value.txt you need the shell make function:
BASE_VAR = $(shell cat path/to/value.txt)
And about your question on debugging variables, the simplest in your case is probably to use the info make function:
$ cat Makefile
BASE_VAR = $(shell cat path/to/value.txt)
DERIVED_VAR = $(if $(BASE_VAR),foo,bar)
.PHONY: debug
debug:
$(info BASE_VAR = $(BASE_VAR))
$(info DERIVED_VAR = $(DERIVED_VAR))
$ make debug
BASE_VAR = blah
DERIVED_VAR = foo
make: Nothing to be done for 'debug'.
But that target-specific variables have different values in different targets. Use $(info ...) in the recipe of the target of interest:
target: VAR = value
target: ...
$(info VAR of $# = $(VAR))
Related
Is it possible to pass value with single dollar from shell to Makefile, or I it is only way to put double dollar in bash and then to call make?
Makefile is:
HASH ?= $$6$$salt$$val
.PHONY: tst
tst:
echo '$(HASH)'
Command to run:
> make HASH='$6$salt$val'
echo 'altal'
altal
If I use double quotes, all is fine:
> make HASH='$$6$$salt$$val'
echo '$6$salt$val'
$6$salt$val
But is it possible do not make substitution $ to $$ in bash?
How about writing the initialisation within the file identical to the one coming from the command line? The below script demonstrates how to rewrite a variable with the override directive:
quote-one-level = $(eval override $1=$(subst $,$$$$,$(value $1)))
var-info = $(info $1=$(value $1) flavour=$(flavor $1) origin=$(origin $1))
A ?= $abc
$(call var-info,A)
$(call quote-one-level,A)
$(call var-info,A)
$(call var-info,B)
$(call quote-one-level,B)
$(call var-info,B)
export A
export B
all:
#echo A = '$(A)'
#echo B = '$(B)'
ifeq ($(MAKELEVEL),0)
$(MAKE)
endif
Inflating one $ to $$$$ (and not just $$) is necessary because the eval command literally generates make code, thereby obviously reducing the quoting level by one. Resulting output:
$ make B='$abc'
A=$abc flavour=recursive origin=file
A=$$abc flavour=recursive origin=override
B=$abc flavour=recursive origin=command line
B=$$abc flavour=recursive origin=override
A = $abc
B = $abc
make
make[1]: Entering directory
A=$abc flavour=recursive origin=environment
A=$$abc flavour=recursive origin=override
B=$abc flavour=recursive origin=command line
B=$$abc flavour=recursive origin=override
A = $abc
B = $abc
make[1]: Leaving directory
Try this:
In console:
export HASH='$6$salt$val'; make
in Makefile:
.PHONY: tst
tst:
#echo "$$HASH"
Result:
$6$salt$val
how do we compare strings in makefile?
in makefile
MAKECMDGOALS ?= debug
DBGDIR = build/debug
RLSDIR = build/release
ifeq ($(MAKECMDGOALS),"debug")
O = $(DBGDIR)
else
O = $(RLSDIR)
endif
I tried following comparisons:
($(MAKECMDGOALS),"debug")
($(MAKECMDGOALS),debug)
($(MAKECMDGOALS),'debug')
($(MAKECMDGOALS), ' debug')
also
ifeq "$(strip $(filter debug,$(MAKECMDGOALS)))" "debug"
but everytime it enter else block and does release build.
Where am i going wrong?
For sure you should not have any quotation marks. The following works for me:
$ cat Makefile
MAKECMDGOALS ?= debug
DBGDIR = build/debug
RLSDIR = build/release
ifeq ($(MAKECMDGOALS),debug)
O = $(DBGDIR)
else
O = $(RLSDIR)
endif
all:
%:
#echo $(O)
$ make
build/debug
$ make foo
build/release
But I would advise against checking it this way, as $(MAKECMDGOALS) may have more than one target and the test will fail:
$ make debug
build/debug
$ make debug foo
build/release
build/release
If you still wish to check this variable, it would be better to check if an interesting target shows among others, i.e.:
$ cat Makefile
MAKECMDGOALS ?= debug
DBGDIR = build/debug
RLSDIR = build/release
ifeq ($(findstring debug,$(MAKECMDGOALS)),debug)
O = $(DBGDIR)
else
O = $(RLSDIR)
endif
all:
%:
#echo $(O)
$ make debug
build/debug
$ make debug foo
build/debug
build/debug
define func1
include $(shell pwd)/test/$(strip $1)/component.mk
$(info :::::::${NAME} ::::::::::::::: )
endef
INCLUDES := a b c
$(foreach dir, $(INCLUDES), $(eval $(call func1, $(dir)) ))
all : $(objs)
Contents of each makefile:
cat test/a/component.mk
NAME := AA
cat test/b/component.mk
NAME := BB
cat test/c/component.mk
NAME := CC
Output is
::::::: :::::::::::::::
:::::::AA :::::::::::::::
:::::::BB :::::::::::::::
It looks like first time NAME is empty.
Let's look at the expansion of $(foreach dir, ${INCLUDES}, $(eval $(call func1, ${dir}) )) in painful detail.
${INCLUDES} is expanded, giving $(foreach dir,a b c,$(eval $(call func1,${dir})))
Next dir is set to a
$(call func1,a) is expanded
1 is set to a
func1 is expanded:
include $(shell pwd)/test/$(strip $1)/component.mk
$(info :::::::${NAME} ::::::::::::::: )
$(shell pwd) becomes HERE, say (N.B. Use ${CURDIR} instead)
$(strip $1) becomes $(strip a) becomes a
${NAME} expands to nothing
$(info ::::::: ::::::::::::::: ) expands to nothing
As a side effect ::::::: ::::::::::::::: appears on stdout
$(eval $(call func1,a)) expands to $(eval include HERE/test/a/component.mk), expands to nothing
As a side effect, the include is processed by make
Presumably HERE/test/a/component.mk exists and contains valid make syntax,
and the variable NAME gets a value.
1 is set to b. Lather, rinse, repeat.
Tip
To get a hint of problems in code like this, always run make with --warn:
$ make --warn -Rr
Makefile:8: warning: undefined variable 'NAME'
::::::: :::::::::::::::
⋮
Fix
To get some insight, replace the $(eval stuff) with $(error [stuff])
$ make
::::::: :::::::::::::::
Makefile:8: *** [ include /cygdrive/c/Users/somewhere/a/component.mk
]. Stop.
Here we see the $(info …) has disappeared even before it has got to the eval.
The naive fix is pretty horrible.
define func1
include $(shell pwd)/test/$(strip $1)/component.mk
$$(info :::::::$${NAME} ::::::::::::::: )
endef
Running this with the $(error …) in place gives
$ make
Makefile:8: *** [ include /cygdrive/c/Users/somewhere/a/component.mk
$(info :::::::${NAME} ::::::::::::::: )]. Stop.
That stuff between the [ and ] is valid make syntax.
Tidied up it looks like:
include /cygdrive/c/Users/somewhere/a/component.mk
$(info :::::::${NAME} ::::::::::::::: )
Job done. There are cleaner ways, but you need to understand the pain first!
My Makefile is based on multiple variables defined in a configuration file or ENV vars. My current solution is to test all of them manually:
NOGOAL = help clean distclean mrproper
ifeq ($(strip $(filter $(NOGOAL), $(MAKECMDGOALS))),)
VAR1 ?= $(error VAR1 undefined)
VAR2 ?= $(error VAR2 undefined)
VAR3 ?= $(error VAR3 undefined)
...
VARn ?= $(error VARn undefined)
endif
I would like to use a foreach loop instead:
ifeq ($(strip $(filter $(NOGOAL), $(MAKECMDGOALS))),)
TESTVAR = TEST1 TEST2 TEST3
$(foreach v, $(TESTVAR), $(eval $v ?= $$(warning Error: $v undefined)))
endif
Unfortunately eval doesn't work as I expected. Did I miss something?
Here a full test of my tests with 2 implementations of the tests. Even if TEST3 is not defined I don't get any error
TEST1 = 1
TEST2 = 1
#TEST3 = 1 # NOT DEFINED
TESTVAR := TEST1 TEST2 TEST3
# First implementation
$(foreach v, $(TESTVAR), $(eval $v ?= $$(warning Error: $v undefined)))
# Second implementation
$(foreach v, $(TESTVAR), $(eval $(call TESTER,$v)))
define TESTER
ifndef $1
$(warning $1 not defined)
endif
endef
# Dummy rule
all:
#echo Hello World
However, my first implementation works if I use $(TEST3) somewhere.
EDIT
Here I get no error but TEST3 is not defined:
~$ cat Makefile
TEST1 = 1
TEST2 = 1
#TEST3 = 1 # NOT DEFINED
TESTVAR := TEST1 TEST2 TEST3
# First implementation
$(foreach v, $(TESTVAR), $(eval $v ?= $$(warning Error: $v undefined)))
# Dummy rule
all:
#echo Hello World
~$ make
Hello World
Well, I guess I don't get it. Your original version, that you say works the way you want it, will not print any warnings unless you USE one of the variables which is not defined. Your first alternative with foreach works the same way: it will print a warning but only when you use the variable that's undefined.
If you want it that way, then testing for clean, etc. doesn't really make much sense since presumably those rules won't use the variables that are not defined so you won't get any errors (and if they did use the variables that weren't defined, presumably you'd want those rules to fail as well).
But in your second edit, you say that you want the make to fail immediately if the variables are not defined, regardless of whether or not they're used (in your last example you don't define TEST3, but you don't use TEST3 for anything either so no warning is printed). If that's what you want I don't see why you are assigning values to the variables with ?= at all, or using eval. Just write something like:
ifeq ($(strip $(filter $(NOGOAL), $(MAKECMDGOALS))),)
$(foreach v,$(TESTVAR),$(if $($v),,$(error Error: $v undefined))
endif
(In this version you do need to check MAKECMDGOALS since it fails immediately on an unset variable).
In Kernel Makefile i found the code like below:
ctags CTAGS CSCOPE: $(HEADERS) $(SOURCES)
$(ETAGS) $(ETAGSFALGS) $(HEADERS) $(SOURCES)
$(call cmd, ctags)
Also, where can i find the Macro or function ?
Using MadScientist's method on kernel v4.1:
make -p | grep -B1 -E '^cmd '
we find:
# makefile (from `scripts/Kbuild.include', line 211)
cmd = #$(echo-cmd) $(cmd_$(1))
scripts/Kbuild.include is included on the top level Makefile. It also contains:
echo-cmd = $(if $($(quiet)cmd_$(1)),\
echo ' $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)
quiet: set at the top level makefile, depending on the value of V.
Will be either:
quiet_ to print CC file.c
empty to print the command on V=
silent_ to not print anything on make -s
escsq is defined as:
squote := '
escsq = $(subst $(squote),'\$(squote)',$1)
It escapes single quotes so that echo '$(call escsq,Letter 'a'.' will print properly in sh.
echo-why: defined further down at Kbuild.include.
It is used for make V=2, and says why a target is being remade.
The setup of make tags is done in the Makefile:
quiet_cmd_tags = GEN $#
cmd_tags = $(CONFIG_SHELL) $(srctree)/scripts/tags.sh $#
tags TAGS cscope gtags: FORCE
$(call cmd,tags)
Which shows the typical usage pattern for calling commands on kbuild:
quiet_cmd_XXX = NAME $#
cmd_XXX = actual-command $#
target: prerequisites
$(call cmd,tags)
A comment on the Makefile explains how all of this is done to make the make output prettier:
# Beautify output
# ---------------------------------------------------------------------------
#
# Normally, we echo the whole command before executing it. By making
# that echo $($(quiet)$(cmd)), we now have the possibility to set
# $(quiet) to choose other forms of output instead, e.g.
#
# quiet_cmd_cc_o_c = Compiling $(RELDIR)/$#
# cmd_cc_o_c = $(CC) $(c_flags) -c -o $# $<
If you run make -p it will print the entire database of all variables, rules, etc. with line numbers where they were last defined.