How to set environment variables in makefile? - gcc

How can I correctly set environment variables in a makefile on Windows?
I get an error about CreateProcess.
C:\>make.exe -f build.makefile start
export MALLOC_PERTURB_=110
process_begin: CreateProcess(NULL, export MALLOC_PERTURB_=110, ...) failed.
make (e=2): The system cannot find the file specified.
c:\testmake.makefile:4: recipe for target 'start' failed
make: *** [start] Error 2
START:
export NODE_ENV=110
echo $(NODE_ENV)

Your question isn't entirely clear but there are a number of obvious things wrong there.
First off you are running make under Windows but writing recipes as if they were shell scripts. That's not the case on Windows (by default at least).
So export is being attempted to be run as an external command which is failing (hence the error message about CreateProcess failing).
You also don't show us the target that is actually throwing that error.
Additionally you are expecting the export and assignment on the first line of the recipe to be in effect for the second line in the recipe body (for the start target).
But that isn't the case. Each line in a makefile target's recipe runs in an independent environment. So the export and assignment on the first line of the START target's recipe doesn't affect the second line.
To do that you need to use one long line or use the .ONESHELL feature of recent versions of make.
Additionally, you are using $(NODE_ENV) in your recipe expecting that to be the shell variable you previously set. And even ignoring the previously stated problem that isn't correct.
make is going to expand $(NODE_ENV) as a make variable before it even runs the recipe at all. You meant ${NODE_ENV} or $NODE_ENV for a shell variable. That said for a make recipe you actually need to escape the $ because ${NODE_ENV} is also a valid make variable expansion. So you need $${NODE_ENV} or $$NODE_ENV there.
Put together you end up with this (assuming you have a shell somewhere to use).
SHELL := /path/to/your/shell
START:
export NODE_ENV=110; \
echo "$${NODE_ENV}"
(though you don't actually need export at that point but that's a different issue entirely).
But if you don't have a shell to use then you get to use cmd.exe and I'm not sure what the equivalent of export there is (though as I just said you don't need it for this) and you end up with something like this (entirely untested):
START:
NODE_ENV=110; \
echo %NODE_ENV%

Related

Export environment variables from child bash script in GNU Make

I have a script "set_env.py" that outputs the following uppon execution:
export MY_VAR_1=some_value
export MY_VAR_2=some_other_value
I cannot change this script, it is supplied in my current environment.
Further I have a Makefile that looks like this:
SHELL := /bin/bash
all: set_env
env | grep MY_VAR
set_env:
eval ./set_env.py
With this makefile I expected the grep to list my two variables, however it seems the environment is not set.
I suspect this is because make creates a sub-environment for each line and so the variables set on the first line will not be available in the second.
So the question is, how would I go about exporting the environment from the untouchable script in my makefile?
Actually, the output of the python is valid make.
One option then is to read the output of the python directly into the makefile.
The only fly in the ointment is that $(shell) doesn't cut the mustard.
include Environment.mk
PHONY: test
test:
env | grep MY_VAR
Environment.mk:
./set_env.py >$#-tmp
mv $#-tmp $#
How does this work?
The first thing that make tries to do is to ensure the makefile itself is up-to-date.
Since we have told it to include Environment.mk,
make must ensure that is up-to-date too.
Make finds a rule for Environment.mk
The python is run, creating Environment.mk
Environment.mk is read in, creating two make variables with the export attribute
The makefile is now up-to-date, so make proceeds on to the target (test in this case)
Make runs test's recipe, exporting any variables with the export attribute.
No recursion, but you should ensure the python always spits out make compatible syntax.
EDIT
As #raspy points out, this is not the whole story.
As it stands,
once Environment.mk has been created,
it will never be regenerated.
If set_env.py ever generates different output,
you should tell make what conditions these are by adding dependencies.
If set_env.py takes a trivial time to run,
I advise a simple .PHONY.
That way it will run every time you run make,
and Environment.mk will never be stale.
.PHONY: Environment.mk
Recursive make is your friend I'm afraid.
.PHONY: all
all:
eval $$(./set_env.py) && ${MAKE} test
.PHONY: test
test:
env | grep MY_VAR
There are a few moving parts here.
make all executes the shell command eval $(./set_env.py) && make test
The shell first does the command substitution
$(./set_env.py) is replaced by the export commands
The export commands are passed to the (shell) eval command
The environment variables are defined, but only for this shell invocation
The eval succeeds, so the execution passes to the command after the &&
Make runs recursively, but this second make has an augmented environment

Changing the stack size and LD_LIBRARY_PATH using a Makefile

I would like to be able to have a rule inside my makefile that a changes the stack size and that appends to LD_LIBRARY_FILE the current directory.
In the shell I can just do:
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$(pwd)
ulimit -s SOME_NUMBER
Is there way to make a rule inside a makefile that is equivalent to running this two commands and will update the environment variables after the makefile is run?
You can link the executables with -z stack-size=VALUE or -rpath, which might have a similar effect.
You could push the command characters to the TTY layer and hope that the shell will execute them, but that is a bit nasty. The makefile could also compile a program which does the job using ptrace, but that would be very ugly as well.
No
A child process in bash cannot effect the environment of the calling shell (as #mpez pointed out). This is done on purpose to avoid some security holes. It's possible to export the commands to change the environment variable to a script, and run that script after you run make (which can be automated through another script), but make itself cannot effect the environment of the calling shell.

export environment variable from a makefile to the system

For one of my project, I need to add something to an env var from a makefile.
Here's a the sandboxed problem :
First, the makefile
all:
$(shell source <(echo export MYVAR=$(MYVAR):otherstuff))
And what I'm trying to achieve
export MYVAR=stuff
make
echo $MYVAR
So technically, MYVAR should contains stuff:otherstuff. But instead of that I got a bash error
/bin/sh: -c: line 0: syntax error near unexpected token `('
/bin/sh: -c: line 0: `source <(echo export MYVAR=$MYVAR:otherstuff)'
I don't know what I did wrong, the command worked outside of the makefile.
Thanks!
And what I'm trying to achieve
export MYVAR=stuff
make
echo $MYVAR
So technically, MYVAR should contains stuff:otherstuff.
As was mentioned in the comments, you can't do it. A copy of environment is inherited from the parent process (the shell where you perform export MYVAR=stuff) by the child process (the make call), and whatever the child process does with the variable, would be visible to the make itself, or its own child processes. But never the parent.
Generally, when I need to export some information from the Makefile, I provision special targets for the purpose, e.g.:
print-env:
#echo export MYVAR=$(MYVAR):otherstuff ";"
#echo export MYOTHERVAR=helloworld ";"
Now when you do make print-env, it would produce the output like this:
export MYVAR=stuff:otherstuff ;
export MYOTHERVAR=helloworld ;
Using the makefile we have generated commands, which could be easily copy-pasted from the output into command prompt to execute them.
Though it is possible and doable, I would advise against the feeding of make's output to the shell directly:
eval "`make print-env`"
or even more radical:
`make print-env`
since make output is generally unstable, and might accidentally contain output of other rules, which might confuse the shell.

shellscripts in Makefiles do not work as expected

I found many answers here and elsewhere on the topic, but none that worked. Please help me out here.
I need to set some environment variables, which is partly done in some scripts, called from a master script, partly directly. Here is a minimal Makefile that shows the unwanted behaviour:
FC := ifort
SHELL := /bin/bash
some_target: load_ifort
$(FC) file.f
load_ifort:
source /usr/local2/bin/ifort-compilervars.sh ia32
export LM_LICENSE_FILE=/usr/local2/misc/intel2013/flexlm/server.lic
if I call make, I get an "ifort: command not found" error. If I execute the two comamnds by hand on the command line before calling make, ifort is found and everything is good.
What am I missing???
Each line in a recipe gets executed in a separate subshell. So you create one shell which sources the .sh file, then exits and forgets everything, then another shell which starts with a clean slate.
The straightforward solution in your case would be to collect all these commands in a single variable. I have factored out the LM_LICENSE_FILE assignment because that can be done in Make directly, but you could include that in the FC variable as well.
LM_LICENSE_FILE := /usr/local2/misc/intel2013/flexlm/server.lic
export LM_LICENSE_FILE
FC := source /usr/local2/bin/ifort-compilervars.sh ia32; \
ifort
some_target:
$(FC) file.f
If the shell commands can be straightforwardly run by Make as well, you could include them, or perhaps translate the sh file into Make commands by a simple script.
Another option would be to create a simple wrapper in your PATH; maybe call it fc:
#!/bin/sh
. /usr/local2/bin/ifort-compilervars.sh ia32
ifort "$#"
then just use fc where you currently have $(FC). (If the ifort-compilervars.sh file contains Bash constructs, in spite of the name, you should change the shebang to #!/bin/bash.)
As a rule, only one-liner shell commands "work". From the comment about "bash", it seems likely you are using GNU make. In your example, the word "source" is not found in the GNU make manual's index. (If you found this in a working example, it would be helpful to start from that). There are two types of variables of interest:
makefile variables, which live in the make program
environment variables, which are "exported"
The latter would include $PATH, which is used to find programs. For updating that, you do need shell commands. But (lacking some special provision in the make program), exported variables from a shell script are not passed up into the make program and made available for the next line of the makefile.
You could reorganize the makefile to provide a rule which combines the source command and other initialization into a shell command which then recurs (carrying those variables along) into a subprocess which would then do the compiles. Something like
build:
sh -c "source /usr/local2/bin/ifort-compilervars.sh ia32; \
export LM_LICENSE_FILE=/usr/local2/misc/intel2013/flexlm/server.lic; \
$(MAKE) some_target"
some_target: load_ifort
$(FC) file.f

How to handle setting up environment in makefile?

So, to compile my executable, I need to have the library locations set up correctly. The problem is, the setup comes from a bunch of scripts that do the env variable exporting, and what needs to be set up may change (beyond my control) so I need to use those scripts instead of copying their functionality. To compile in regular command line, I need to do something like:
setup library1
setup library2
source some_other_setup_script.bash
g++ blah.c
# setup is a executable on my system that run some scripts
How would I write a makefile that accomplishes that? As far as I tried, the env variable exporting does not carry over (i.e. "export VAR=remember; echo $VAR" won't work)
You can also add environment variables properly with the machinery of GNU make, like so:
export TEST:="Something Good!"
test:
echo $$TEST
This (I think) has different semantics from:
TEST2:="Something not quite so useful?"
test2:
echo ${TEST2}
Which (again, I think) does the substitution within make before passing along to the shell. Note that the export command doesn't work within a target block, just unindented as an immediately executed command.
If variable exporting is not working the way it does on your command line, that suggests that Make is choosing a shell different from the one you're using, with different syntax for handling variables (export VAR=remember; echo $VAR works fine for me). Make uses /bin/sh by default, but you can override this with the SHELL variable, which Make does not import from the environment. I suggest setting SHELL (in the Makefile) to whatever you're using in your environment and trying the export VAR=remember experiment again.
Ultimately you will need to define the variable and execute the compiler in a shell list or even a script, rather than in separate make commands. There are a couple of refinements you could add, however. You could tell make about the script:
maintarget: script.sh blah.c
source script.sh; g++ blah.c
script.sh:
setup include script here
Another thing would be to just execute all that stuff in the same shell
maintarget: blah.c
run this; run that; run the other thing; g++ blah.c
I believe all make versions will run a ; list in the same shell, but you can always force a subshell with (list) or by calling specifically a shell script as a compiler command wrapper.
Don't forget to have the appropriate targets depend on your scripts themselves. BTW, some make versions (pmake aka bsd make) can execute a command when defining a make variable, and all versions of make then exports those. But I don't think gmake can do that.
You could write another shell script that executes all those commands, then prints out variable assignments that make can use. Run the script, pipe its output to a file, then include that file from your Makefile. For example:
Makefile:
all:
echo $(FOO)
test.mk: test.sh
./$< > $#
include test.mk
test.sh
echo "FOO=1"
Running "make" in the directory containing this Makefile produces:
make: Entering directory `/home/luser/build/mktest'
Makefile:7: test.mk: No such file or directory
./test.sh > test.mk
make: Leaving directory `/home/luser/build/mktest'
make: Entering directory `/home/luser/build/mktest'
echo 1
1
make: Leaving directory `/home/luser/build/mktest'
make creates test.mk by running the shell script, then includes it. test.mk contains the output of test.sh, and is parsed as a Makefile. See http://www.gnu.org/software/make/manual/make.html#Include for more details.
We use a variant of this in Mozilla's client.mk to let you define options in a "mozconfig" file:
http://mxr.mozilla.org/mozilla-central/source/client.mk#138
Restatement: How do I get a shell variable into a make file?
Something like:
MYVAR := $(shell echo $(MYVAR)) <any_makefile_additions_here>
So, this defines MYVAR inside a MAKEFILE when an environment variable named MYVAR is also set.
It might be of interest, that, in order to override an option that is already defined in a makefile, make supports (I am referring to GNU Make 3.82, but other version probably too) the option -e.
Example:
Makefile:
CC=gcc
...
Run make:
CC=gcc-4.7
make -e
will use gcc-4.7 instead of gcc.

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