Makefile unset variable. Improve this question.

Makefile unset variable Variables are the bread and butter of every programming or scripting language, including PowerShell. UNAME=@@UNAME@@ in it. Are you trying that? How are you using it in dir1. It is because all the variables are set only in "setup" target. The argument(s) passed to the shell are taken from the variable . o foo. Somewhere in the makefile there is a variable defined: FOO=hello Later on I need to append some text to FOO's content. However, an explicit assignment in the makefile, or with a command argument, overrides the environment. Edit: In the Makefile is: BROKEN= does not link And I want to unset/undefine broken. Makefile::AST::Variable It represents Variables may also be left unset in the makefile. Alternatively, you can unset environment variables by using the set command with the “-n” flag. o bar. Since its replacement is not universally available (despite the comments a while back in Re: [Fedora FWIW (just adding a usage scenario comment, to affirm what I see as the core of this answer), using LDLIBS instead of LDFLAGS is definitely a game-changer for the case of a simple foo. c cc -c -o b. but I would like to set the sh variable on the same line inside the makefile As a developer, you’ve likely encountered situations where you want to abort Makefile execution if a specific variable is not set. 2 Choosing the Shell. These variables are defined in the sub-make as defaults, but they do not override variables defined in the makefile used by the sub-make unless you use the ‘-e’ switch (see Summary of Options). Another way to do this is by using a "configure" script. shift. How to set Makefile variable and make on Mac OS X? 0. The most common way to use this facility is to pass extra flags to compilers. However, if I make the Makefile invoke itself, then MAKEFLAGS= --warn-undefined-variables works in the child invocation!. On other BSD systems, I do it like this: env -u MAKEFLAGS $(MAKE) $(SUBDIR_ARGS) On Linux, I do it like this: env --unset=MAKEFLAGS $(MAKE) $(SUBDIR_ARGS) I don't think that's a problem. Only doing echo $(BLAH) is merely evaluating Makefile's key/value mechanism inside the Makefile. Stop. If the variable is empty, the test How do you unset a variable in Makefile? You have to give the NAME of the variable to undefine. o) $(OBJS): $(SRCS) cc -c -o a. The MAKEFLAGS variables will pass these options and variables down to each sub-make. 81 (the default on macOS Catalina), the updated PATH is correctly reflected in variables (echo $(PATH)) and within commands' environments (env, which python, bash -c python), but does not seem to be used when locating the executable for the command: the Setting Makefile variable from recipe in Makefile. Since its replacement is not universally available (despite the comments a while back in Re: [Fedora FOOBAR is being evaluated because you are running a recipe (for clean) and FOOBAR existed in the environment on entry to make. o’. It doesn't explain Makefile variable assignment, which may happen inside recipe execution when the shell (bash) is usually executed, not the Makefile environment itself. A shell command, unless in the context of the make-function $(shell ) or back-ticks can only be a command within a recipe: I have a makefile, which includes several other makefiles, which in turn all add to a variable like this: VAR := Something SomethingElse VAR += SomeOtherThing can we undefine/unset a variable in makefile. You may need to set the . From this answer here, I understand that you can even create pseudo local variables that way, by automatically prefixing them with the target. However, when I run it prints an I really encourage you to NOT try grabbing examples from other complex makefile setups, until you understand makefiles or are willing to read through the GNU make manual to understand what you're cutting and pasting. ) with local values, effectively erasing the value I chose in the top-level Makefile: 8. But make cannot set environment variables for shells that invoke make. When it is time to execute recipes to update a target, they are executed by invoking a new sub-shell for each line of the recipe, unless the . export variable export Also it shows that using a variable with single dollar (${LINE}) just gives you a blank (because the makefile doesn't interpret it as a shell variable). Your original shell snippet could be something like: result=$(if $(filter y,${CHECK}),true,false) (TIMTOWTDI applies). "$@" With zsh, you To unset a bound variable in bash use unset VARIABLE (unset ALL_PROXY in your case). Update: This is not possible according to . c b. env, which make requires to be escaped. 5. Your problem is that you're using a simple assignment for PERL_RUNNER. Overwrite variable from makefile. Hot Network Questions PSE Advent Calendar 2024 (Day 9): Expanding such a variable will yield the same result (empty string) regardless of whether it was set or not. And, you should not add quotes around entire values in make variables like you do in shell variables: make variables do not need quoting. NublaII NublaII. If you want to set the variable in the makefile even though it was set with a command argument, you can use an override directive, which is a line that looks like this: 9. If a variable has been set with a command argument (see section Overriding Variables), then ordinary assignments in the makefile are ignored. It will seriously limit the use you can make of them (basically to recipes). The assignment of the named variables in a let expression is in effect only within the text provided by the let expression, and this assignment doesn’t impact that named variable in any outer scope. You switched accounts on another tab or window. Suppose you are writing a pattern rule to compile a ‘. The MAKEFLAGS variable is automatically set up by make, and it contains all the flags and command line variables that you passed to the top-level make. I want to fill in a variable according to the contents of a directory after Rebar runs. Make will expand the argument to undefine so if the variable ENV_VAR_TEST is set to the value foo, then undefine I have a Makefile that has a variable that needs to have a default value in case when variable is unset or if set but has null value. If you want the change to persist across invocations of make, not just between targets within a single invocation of make, that's an To remove an environment variable, run. Make does not know anything about shell variables. You will not be able to use them as targets, prerequisites, other variables definitions, conditions of make conditionals. But another is left as default. (If the ‘-e’ flag is specified, then values from the environment override assignments in the makefile. ONESHELL will do that since it uses far fewer shell invocations. Thus, if the first thing a makefile does is examine the last word in this variable, it will be the name of A conditional causes part of a makefile to be obeyed or ignored depending on the values of variables. Environment variable name: TEST, its value: "TRUE" test_target: ifeq ($(TEST),"TRUE") echo "Do something" endif I get the following error: /bin sh: 2: t: not found is a result of trying to execute the command t. Is there a simpler way to get a default value on unset variable? If you want to use the expansion of a GNU make variable if it is non-empty and a default value if it is empty, but not set the Sure you can read input from the user within a Makefile. Remember that every command is run in its own shell, so dateString and revision will be unset in third and fourth command. 1. You can cancel all variables used by implicit rules with the ‘-R’ or ‘--no So if you want a global variable you just remove the target part (e. The conditional assignment implicitly creates a normal (recursive) one, so I need to do either Hi all, @ulfalizer is correct. 9. 0. Conditionals control what make actually "sees" in the makefile, so they cannot be used to control shell commands at the time of Just to be clear: make doesn't put all make variables into the sub-make's environment. – Include another makefile. They allow you to store information and use it later in your script. Commented Nov 6 I'm working on a go project which has a Makefile like below. Tried hard, but can't find it. Extra spaces are allowed and ignored at the beginning of the conditional directive line, but a tab is not allowed. You can tell make to use a different shell by assigning a value to the SHELL variable (i. 7. Hot Network Questions One of my colleague's largest publication seems to be plagiarized/purely reproductive-What to do? Another approach to 'getting your multi-line variable back out of the makefile' (noted by Eric Melski as 'the tricky part'), is to plan to use the subst function to replace the newlines introduced with define in your multi-line string with \n. – Expanding such a variable will yield the same result (empty string) regardless of whether it was set or not. It looks like it is evaluating what the file is like when make is first run, which is not what I want. c as well which is probably not the case. For the life of me, I cannot get it to work. here is my code: build: @read -p " Enter Module But I need a makefile variable changed, module is a local file. SHELLFLAGS. You signed out in another tab or window. I tried it like this: FOO=$(FOO)_world I suggested that echo $(FOO) would output hello_world. This helps us use the same variable name where needed. g. Additionally, the "Launch target" section also should be associated with your executable file path. What you're probably after is a single rule on how to turn one file type into another: Whenever I mention any version along with the execution command of this makefile that version should be stored in the variable VERSION, if no version is mentioned the default value should be taken How to remove trailing spaces from makefile variable? 0. 2 Communicating Variables to a Sub-makeVariable values of the top-level make can be passed to the sub-make through the environment by explicit request. override variable-assignment. (See the Base Definitions volume of IEEE Std 1003. If a variable has been set with a command argument (see Overriding Variables), then ordinary assignments in the makefile are ignored. 30. GNU make supports some variables that have special properties. The assignments in the define aren't happening until the define expansion is processed by eval so your assigned variable value isn't visible until later. How can I achieve this? I need this, as I To prevent Makefile execution if a variable is not set, you can employ several methods: The test command allows you to check if a variable is set or empty. This is not really equivalent to the code in the question. Doing that will make SECONDS available but will still not allow you to carry a variable value between recipe lines as each recipe line is run in its There are many SO answers that will describe to you the difference between make variables and shell variables; knowing this difference is crucial to writing makefiles. 34. Conditionals can compare the value of one variable to another, or the value of a variable to a constant string. This makes a difference when testing for existence of files generated by the Makefile. However, if you are running make without a specific makefile, a makefile in MAKEFILES can do useful things to help the built-in implicit rules work better, such as defining search paths (see Searching Directories for Now, while having . /node_modules/. Variables defined with ‘:=’ or ‘::=’ are simply expanded variables; these definitions can contain variable references which will be expanded before the Expanding such a variable will yield the same result (empty string) regardless of whether it was set or not. SHELL=bash to get an echo that does this. mk need it). In a makefile, variable not overwritten despite showing it has a different value and which also results in wrong ifeq 0 Makefile wildcard function evaluates to true against empty string Go to the previous, next section. Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company A conditional causes part of a makefile to be obeyed or ignored depending on the values of variables. How to Use Variables. Instead I get an error: *** Recursive variable 'FOO' references itself (eventually). 5. For example, it's useless to just set a variable: clearly you want to USE that variable somewhere. I have a Makefile target, in which I have to check the value of an environment variable. The above doesn't assign a value to the variable and I'm guessing this is due to the priority of the execution of lines. Ask Question Asked 3 years, 6 months ago. If I type this manually in makefile it works, however when using the double dollar symbol it seems like it is not able to evaluate the variable FOLDERS. When rulea is invoked, it . It lists the other files that the targets depend on, called the prerequisites of -z checks both for empty or unset variable. c if any libraries needed are in LDLIBS, but defines a variable named objects to contain the value ‘main. Modified 3 years, 6 months ago. c OBJS=$(SRCS:. A compliment of Renaud Pacalet: What you are assigning to your make variables are shell commands, not the result of their execution by the shell. 3 Variables Used by Implicit Rules. To get this to work, simply export the variable names you want to be present in your recipe execution environment. in sh, assignment does NOT allow whitespace. The kconfig paths are not passed to the linker script generator (ldgen. The [and ] clearly delineate the variable expansion. Here's an example. To test this, create a directory called subdir and create a makefile in this subdir with the following content: I have a Makefile. If you want to set the variable in the makefile even though it was set with a command argument, you can use an override directive, which is a line that looks like this: override variable = value. var. 6k 22 22 gold badges 109 109 silver badges 133 133 bronze badges. ) you don't really need to unset the variable anywhere if you only use it in the toplevel makefile to add/etc. c I want to trigger unit test and integration test in a Makefile, my current implementation is like this: all: unittest integration unittest: $(ECHO) @echo 'Running unittest' @unset TYPE @ if I set the environment variable manually with export TYPE=integration, then I run make unittest, the environment variable would not be unset Is there a simpler way to get a default value on unset variable? bash; gnu-make; variable-expansion; Share. This appendix summarizes the directives, text manipulation functions, and special variables which GNU make understands. 1 What Makefiles Contain. 1 Basics of Variable References. 5 The let Function. How to conditionally set Makefile variable to something if it is empty? 7. The only way we can tell you the right way to set the variable is if we know how you want to use it / what you want to use it for. In python, you can print(os. PHONY: foo VAR_GLOBAL=$(shell cat /tmp/global) foo: echo "local" > /tmp/local With that said, makefile is not the right tool to do what I do here, but I gotta comply with some standards. DEFAULT_GOAL. Yes, . I have a makefile where I want to read module name from input and then make directory based on its name. 3. Moreover, if one of the original . This assumes your make supports += syntax. You can also set the value of a How do I change variable value dynamically in makefile? I want to call specific target depending on value of macro. There is no such thing as There are many SO answers that will describe to you the difference between make variables and shell variables; knowing this difference is crucial to writing makefiles. 10. mytarget: $(eval $@_foo = bar) @echo mytarget: $($@_foo) other: mytarget @echo other: $($@_foo) By default make uses /bin/sh as the shell which executes recipe lines. Or don't use intermediate variables, then you won't need it to be one command. 7 The override Directive. bashrc for bash). mk makefile it will be set when that makefile goes to look for it (unless it gets unset later before the contents of dir1. Is there a way to declare this makefile variable as a prerequisite of the deploy recipe? e. But, I don't get the exact syntax of it. trunk/Makefile is an example of a Makefile is is called multiple times by itself. However, if you are using the flavor (see The flavor Function) and origin (see The origin Function) functions, there is a difference between a variable that was never set and a variable with an empty value. or How could I abort a make/makefile execution based on a makefile's variable not being set/valued? I came up with this, but works only if caller doesn't explicitly run a target (i. Since you only set make's variables, obviously references to shell variables of the same name would result in empty values. Something like this: What does the @ sign inside of the substitution reference in this Makefile recipe mean? I know it's not echo suppression and I'm fairly confident it's not an automatic variable (at least one that I know of). Contains the name of each makefile that is parsed by make, in the order in which it was parsed. Once it exits, everything that that invocation of make knew is gone. makefile Share Make allows you to define variables, which are very convenient for dealing with the type of “problem” considered above. See The override Directive. ONESHELL special target is in effect (see Using One Shell) (In practice, make may take shortcuts that do somevariable1 will be assigned during interpreting the makefile, before executing any recipe. This target filters out and prints all the variables that were defined in a makefile: 10. Commented Aug 6 at 11:20. py) properly unlike when build is invoked from MSYS. Improve this question. Any help is appreciated. See section Special Built-in Target Names, section Catalogue of Implicit Rules, and section Summary of Options, for other summaries. Doing that will make SECONDS available but will still not allow you to carry a variable value between recipe lines as each recipe line is run in its I have a Makefile that has a variable that needs to have a default value in case when variable is unset or if set but has null value. I want to assign variables in foreach loop based on some condition. make doesn't special-case echo; it just All the make variables are gone by the time the shell gets its hands on the recipe. PHONY: all all: echo $(MYVAR) I'm trying to put together some complicated makefile rules to automate building a project against multiple compilers. You can use eval to set variables in a recipe. – I want to assign variables in foreach loop based on some condition. Expand variables after filtering them out. These values are substituted by explicit request into targets, dependencies, commands, and other parts of the makefile. I always recommend that ALL make variable assignments use whitespace around the assignment operator: this helps remind yourself of the difference since shell variables cannot have spaces around the =. Do include the ‘-g’ option in CFLAGS, because that is not required for proper compilation. setting a target default: foo, with no other explicit settings, will successfully build foo from foo. Here is a summary of the directives GNU make recognizes: I have the following in my makefile. And to pass this to makefile I have to set it inside bash-script. answered Jun 29, 2012 at 14:56. I have one rule that creates some dynamically generated variables and assigns 6. Hot Network Questions How to avoid killing the wrong process caused by linux PID reuse? Best way to stack 2 PCBs flush to one another with connectors Now I want to use these variables in all make targets. Additionally, the let function enables list unpacking by assigning all unassigned values to the It usually is not desirable to set the environment variable before a top-level invocation of make, because it is usually better not to mess with a makefile from outside. bin/gulp ifeq ($(MY_SERVER_ENV), How could I abort a make/makefile execution based on a makefile's variable not being set/valued? I came up with this, but works only if caller doesn't explicitly run a target (i. I'm working on a makefile rule and wish to unset the environment variable MAKEFILES before invoking make again recursively. Rules, variables, and directives are described at length in later chapters. /bin export PATH echo $(PATH) GNU Make also allows you to specify the default make target using a special variable called . Improve this answer. Since you don't actually say why you want to do this we can't give you any advice on a better way to write your makefile. – Also it shows that using a variable with single dollar (${LINE}) just gives you a blank (because the makefile doesn't interpret it as a shell variable). The value of these variables will be present in your makefile, but not your environment. Understanding the Problem Makefiles are widely used in software As with automatic variables, these values are only available within the context of a target’s recipe (and in other target-specific assignments). To pass down, or export, a Default make receives environment variables. c=. $ go test -tags=integration -v -race Inside my makefile, I need to set a variable based on an environment variable called MY_SERVER_ENV. When you use parens, like $(fOO), in your command, you refer to the make's variable. It details the different behavior of the SHELL variable and how it is, or isn't inherited from the shell make is invoked from on different platforms. EFLAGS += -I$(PWD)/include EFLAGS += -pa $(PWD)/ebin ## $(PWD)/deps/* will only have contents after Rebar runs EFLAGS += $(patsubst %,-pa %,$(wildcard $(PWD)/deps/*/ebin)) build-deps: . Anything anywhere in a makefile of the form $() is evaluated by make unless it escaped as $$() in a shell command. SHELL := /bin/bash). SRCS=a. Though I don't have the permissions to change the Makefile I am looking for possibility to undefine the broken? variable. An example of such 'make abuse' is the OpenWRT buildsystem. Charles How to conditionally set Makefile variable to something if it is empty? 0. – Etan Reisner. Assuming make is GNU Make, all the environment variable settings inherited by make are automatically registered as make variable settings. Skip to main content. In this case they are implicitly set to the empty string "". env files You do this by setting the SHELL variable in the makefile to what you want like: SHELL := /usr/bin/bash For more information checkout this section of the GNU Make manual. This is not related to compiler flags so far. From the GNU make manual:. It is possible to recursively use the Makefile multiple times. For example in practice I want to use it for going through all required tools Defining makefile variable at build time and using it in foreach. The config makefiles is included in the current build by setting the MAKEFILES env var, and the actual build makefiles reference these varaibles when building and linking to artifacts in these directories, so e. Building software that uses LLVM does If 2. . All the make variables are gone by the time the shell gets its hands on the recipe. If a make variable is exported and unset, that make variable will have the value of the corresponding env variable and be present in all shell contexts. They will make reading your code and debugging harder. o depends on b. Variables defined with ‘=’ are recursively expanded variables. Reload to refresh your session. Here's the relevant strip of the makefile: PATH := $(shell pwd)/bin:$(PATH) install: mkdir -p . And for many other tasks. When you start make again, it has gone back to the default. There are ways to get around this however, If you want to set the variable in the makefile even though it was set with a command argument, you can use an override directive, which is a line that looks like this: override variable = value. MAKEFLAGS= --warn-undefined-variables $(info MAKEFLAGS: $(MAKEFLAGS)) EDIT completely reworked the answer after the OP explained in a comment that he wants the environment variables to be defined for any user shell. ifndef variable-name. Your recipe is running in a shell which is a separate process than make: make's variables cannot be modified based on the algorithm that's running in the shell. I've submitted a fix internally, the patch file is provided below for you to verify if it works. and the latter doesn’t see the environment variable. For example, sets " CFLAGS " to the string "". VARIABLES was modified in your makefile, the two most voted answers won't catch it. o, but this The $(info) output issue is what I explained in the comments on this answer of mine. There are also many SO answers that will explain that each command in a recipe is run in a different shell, and that variables set in one shell can't be passed to another shell, so setting a variable in one When you use curly braces, like ${FOO}, in your command, you refer to a a shell variable, as defined in the shell invoking make. There are also many SO answers that will explain that each command in a recipe is run in a different shell, and that variables set in one shell can't be passed to another shell, so setting a variable in one can we undefine/unset a variable in makefile. I want to do this because I change the variables quite a bit and the structure of my Makefile has many intermediates that are occasionally difficult to trace back to their literal file paths, but are easy to make based on the variable names that I have assigned them. Example: def_rule: ifeq ($(TARGET), android) CC=arm-linux-androideabi-gcc else echo "native build" endf all: def_rule tp xi_eid_chipset. Note that the "release" target sets two environment variables so that the "build" target cross-compiles for a your observation about setting env vars on the command line has inspired the answer, I can just unset them on the "test" command so it uses the local 10. The code is like this: ifeq ("$(origin O)", "command line") KBUILD_OUTPUT := $(O) endif But when I try to output KBUILD_OUTPUT in the target's make process, for example, the target help, I find it is not defined. Stack host> unset SPL_VAR host> make ruleb SPL_VAR undefined, aborting make: *** [Makefile:4: Downside to this is that . You can certainly set environment variables that will be in effect for programs make will invoke. Again, to be clear: "make -d" is not a solution. e. This command actually deletes the variable. Instead I recommend you go through a basic makefile tutorial and get a simple makefile working, then try to extend it. txt doesn't exist then the variables are not set. The other will be assigned as the recipes are processed. txt exists before running this the variables will be set to the data prior to running make (not the new redirected data), if 2. First, please be clear about the difference between environment variables and make variables. env file. Because FOOBAR existed in the environment on entry, it becomes an exported variable, which means that make will provide it as part of the environment to any program in the recipe. runs make only). An added benefit is we only need to make one change if we need to change the value. The wildcard substitution takes place while the Makefile is parsed, whereas for instance the shell commands can take place only once a Makefile rule is executed. Only variables which were in the environment that make inherited from its parent, plus any variables explicitly specified as export in the makefile, will be exported to the sub-make via the environment. I'm trying to add to the PATH, the bin folder inside wherever the Makefile directory is. That means that the right hand side of the assignment is expanded immediately as the makefile is parsed. Commented May 21, 2021 at Yand BUILD variables are simply expanded variables because they're assigned using := (and not =), see the manual for more information. As ifeq can be run only in rules, I have added an additional rule (def_rule) I refer to for each rule. So you can just write, e. – Alexander Fadeev. $ export SOME_ENV=someTest. o a. Variables and functions in all parts of a makefile are expanded Beware before using this solution. I am trying to set an Environment variable in a Makefile, so it can be used in another program running in the sam shell as make, but after make has run. Makefiles contain five kinds of things: explicit rules, implicit rules, variable definitions, directives, and comments. Variables can represent: lists of file names; options to pass to compilers; programs to run; directories to look in for source files The export directive worked for me (thanks!), but only after I installed GNU Make 4. Whitespace around the variable name and immediately after the ‘=’ is ignored. (In some other versions of make, variables are called macros. someTest. I would appreciate knowing a way around this problem. Immediate Set VARIABLE := value Setting of a variable with simple expansion of the values inside - values within it are expanded at declaration time. Expanding such a variable will yield the same result (empty string) regardless of whether it was set or not. : $(FOO)" @echo "" @while [ -z "$$CONTINUE" ]; do \ read -r -p "Type anything but Y With some shells, you can instead create a local scope for the variable using a function: local "$1" # $1 variable declared as initially unset in bash¹. /rebar Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company That doesn't work because every line in a makefile rule is run in its own shell instance. So if your makefile runs a program then you can set an environment variable in your makefile that will be visible in that program. Makefile variable assignment based on an existence of a directory. You could also use " and " or similar. Put CFLAGS last in the compilation command, after other variables containing compiler options If 2. Do you want to define this variable for use in that same rule? Some other rule? Etc. – I always recommend that ALL make variable assignments use whitespace around the assignment operator: this helps remind yourself of the difference since shell variables cannot have spaces around the =. 14 Other Special Variables. Consider the Makefile below. Share. Makefile: eliminate element from a list. I cannot set multiple variables depending on target. They allow us to store values that we might want to use in a lot of places. mk? – 6. Is there any way to set env variable in top level Makefile and unset when done Hello I have compilation directory structure the top level Makefile is the one that contains all the sub directories I want to set in this Makefile env variable say : setenv OPTIMIZATION_LEVEL "1" and when all the sub directories done compiling it will set this variable to different lavel. How can I define the default value for a variable in mkfile. Makefile - Subst - not replacing variable. The code I modified is like this: I am trying to figure out how to use env variables in makefiles. It not only builds its own software, but it can build yours too. Then use -e with echo to interpret them. You have to give the NAME of the variable to undefine. ). Makefile (1) ifdef myvar MYVAR := $(myvar) else MYVAR := default endif . c is evaluated when the makefile is parsed, not when the struct rule is invoked, and expands to: wat: . Self promotion: You can find other articles on my website 😉 Problematic When creating some make commands in your Makefile, you may want to have some parameters accessible to the user, so If you have the variable set when you include the dir1. By the syntax here it looks like you're trying to set a make variable COMPILER_CMD from within a recipe based on the value of some shell boolean test, which is of course impossible. If the variable variable-name has an empty value, the text-if-true is effective; otherwise, the text-if-false, if any, is effective. If $(BAR) produces a dollar sign, that dollar sign is now just data inside FOO and won't be causing any more problems. 10 Variables from the Environment. Hot Network Questions PSE Advent Calendar 2024 (Day 9): basically, the first line creates a file called "supercell. That said it also drastically changes the semantics of the build (since failures on any given line won't abort the build immediately) at least not without "modif[ing] . mk run : setup # export all the variables # do domething Now when I do make run I cannot see the variables being set. Either You can test environment variables with Makefile conditional syntax, like this: sometarget: ifndef MY_APP @echo "MY_APP environment variable missing" exit 1 endif somecommand to_run_if_my_app_is_set Note that ifndef/ifdef operate on the I have a Makefile. 169 1 I'm having some trouble in exporting the PATH I've modified inside the Makefile into the current Terminal. <variable>=<value> In fact in sh, you can write: A=1 B=2 myprogram and it will set two the variable for the execution of a program, but not retain them beyond that. In this comprehensive 2600+ word guide for experts, we dive deep into use cases, advanced applications, best practices, and custom usage of makefile variables and arguments. Arguments allow injecting values into variables override defaults when invoking make. SHELLFLAGS to add the -e option to the shell which will cause any failure anywhere in the command line to cause the shell to fail" and -e isn't I have the following in my makefile. There are also many SO answers that will explain that each command in a recipe is run in a different shell, and that variables set in one shell can't be passed to another shell, so setting a variable in one There is only --warn-undefined-variables which will generate a warning, but not an error, and it only warns on undefined variables, not empty variables (these are not the same thing). That means you can't set a makefile variable from within it. Which seems to sort of work but still causes the ifndef to be invoked if a target further down in the Makefile (which does not require the variable to be set) is invoked. I have a target to "clean" my locally installed test/staging-server. What you're probably after is a single rule on how to turn one file type into another: It's also doable without saving all the . So you use semicolons and backslashes at each line's end to make it one command. o and if you put this in a makefile: main: echo value is ${ABC} (except don't copy paste that because my tab is actually four spaces) and then pass it into the file like this: $ ABC=123 make main echo value is 123 value is 123 everything works as expected. rulea: echo rulea ruleb: echo ruleb I want an environment variable SPL_VAR to be defined when ruleb is invoked, or abort otherwise. To substitute a variable’s value, write a dollar sign followed by the name of the variable in parentheses or braces: either ‘$(foo)’ or ‘${foo}’ is a valid reference to the variable foo. This means that the $(TARGET) in the prerequisite: wat: $(TARGET). Makefile variables provide a way to store configurable settings for reuse across build tasks. I need to set two variables for example if makefile has been run with option cpp (target), two variables should be set,but I get only one variable (CC) set. You should export the variable using Make’s constructs: export SOME_ENV := someTest test: go test or specify the variable inline: test: SOME_ENV=someTest go test or ensure both lines are run in the same shell: test: export SOME_ENV=someTest && \ go test I want to trigger unit test and integration test in a Makefile, my current implementation is like this: all: unittest integration unittest: $(ECHO) @echo 'Running unittest' @unset TYPE @ if I set the environment variable manually with export TYPE=integration, then I run make unittest, the environment variable would not be unset This is not possible. Presumably /bin/sh doesn't support the SECONDS variable. Commented Nov 17, 2017 at 14:11. In C and C++, a basic language feature is variables. Any directory under projects that has both a configure script and a Makefile is assumed to be a project that uses the LLVM Makefile system. An explicit rule says when and how to remake one or more files, called the rule’s targets. Makefile::AST::StemMatch This class encapsulates the file pattern matching (file names containing "%") and stem substitution algorithms. Global variables have their place but try to minimize their usage. The name is appended just before make begins to parse the makefile. In version 3. In make, assignment is <variable> <whitespace> = <whitespace> <value>. The program used as the shell is taken from the variable SHELL. Makefile test if variable is not empty. Projects ¶. In one of my Makefile recipes, I want to create a temporary file, pass the name of that file to a shell command and assign the output of that command to a make variable so that I can use that subsequently. This package provides two interactive functions: setenv-file: Set all the environment variables defined in an env file. The recipes in built-in implicit rules make liberal use of certain predefined variables. Its a GNUmakefile, so the additional make features are supported: # Undefined Behavior Sanitzier (CRYPTOXX_UBSAN= or CRYPTOXX_SAN=ubsan, etc. You can do that, as per the following:. (TEST_ENV_ONE)' $ unset TEST_ENV_ONE $ printenv TEST_ENV_ONE $ eval "$ How can one use the variable defined inside a make target . Check out $(origin) function. See Including Other Makefiles. You can cancel all variables used by implicit rules with the ‘-R’ or ‘--no /bin sh: 2: t: not found is a result of trying to execute the command t. I have one rule that creates some dynamically generated variables and assigns Well sure: running make switch changes the value of the ACTIVE variable for that invocation of make. Unlike most variables, the How to conditionally set Makefile variable to something if it is empty? 7. See 6. Quick Reference. You have an evaluative order problem. $(flavor $*) tells you what kind of variable it is. 3. If you want the change to persist across invocations of make, not just between targets within a single invocation of make, that's an I have an external tool that fetches some sources (). but I would like to set the sh variable on the same line inside the makefile How to Use Variables. – How to set a global variable itemname in my masterfile, available to my sub-makefile ? Note: My project is actually more complex, with 12 different sub-makefile, which should reuse the same parameters/variable from the master file. You are setting make variables here, not environment variables. Hot Network Questions PSE Advent Calendar 2024 (Day 9): Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company I have a makefile, which includes several other makefiles, which in turn all add to a variable like this: VAR := Something SomethingElse VAR += SomeOtherThing can we undefine/unset a variable in makefile. That expansion is done when FOO is assigned because I used an immediate variable (:=). Variables and functions in all parts of a makefile are expanded $($*) expands to the value of the variable whose name is given by by $*. 31. 6. o utils. You can consider it a default that is only recommended. The let function provides a means to limit the scope of a variable. I have one problem. If you are already using one with your makefile, you can use a combination of uname and sed to get things to work out. By default make uses /bin/sh as the shell which executes recipe lines. That way I can let the variable depend on itself and use normal Make utilities to conditionally set it. all: @echo "Text from env. (TEST_ENV_ONE)' $ unset TEST_ENV_ONE $ printenv TEST_ENV_ONE $ eval "$ A Makefile deploy recipe needs an environment variable ENV to be set to properly execute itself, whereas other recipes don't care, e. You need extra eval's or post-eval expansion to do that. If the package is set up so that it is compiled with GCC by default, then you might as well include ‘-O’ in the default value of CFLAGS as well. Referencing a variable before making on shell prompt, SOME_ENV is set and the next command (go test) internally picks . I'm trying to put together some complicated makefile rules to automate building a project against multiple compilers. Built into the system is knowledge of the llvm/projects directory. ifeq ($(MY_FLAG),) abort: ## This MUST be the first target :( ugly @echo Variable MY_FLAG not set && false endif all: @echo MY_FLAG=$(MY_FLAG) I have a variable in my makefile I would like to either unset or redefine, so that targets a, b and c use the correct value of MY_VARIABLE If I put unset MY_VARIABLE; echo ${MY_VARIABLE} in prep_foo, I still get the old value of MY_VARIABLE echo Well sure: running make switch changes the value of the ACTIVE variable for that invocation of make. , deploy: make-sure-ENV-variable-is-set makefile; Share. c -> foo via implicit rules type build (e. 5 Overriding Variables. Also the fact that make treats tab as special means that it will attempt to interpret tabs as meaningful inside . unset ALL_PROXY Note that an environment variable only takes effect in a program and the program it launches. I have a variable in my makefile I would like to either unset or redefine, so that targets a, b and c use the correct value of MY_VARIABLE If I put unset MY_VARIABLE; echo ${MY_VARIABLE} in prep_foo, I still get the old value of MY_VARIABLE echo Simply always use the VAR += word syntax in your Makefile, instead of VAR = word. Conditionals control what make actually "sees" in the makefile, so they cannot be used to control shell commands at the time of There are many SO answers that will describe to you the difference between make variables and shell variables; knowing this difference is crucial to writing makefiles. This is achieved by prefixing the variable with $@_. – MadScientist I'm assuming that the example you show is the recipe for some rule. The kernel Makefile init the variables like KBUILD_OUTPUT outside any target's make process. 0 here and I cannot for the life of me get make to honor MAKEFLAGS= --warn-undefined-variables with a straightforward Makefile. Follow edited Jun 12, 2022 at 21:57. o’ file: how do you write the ‘cc’ command so that it operates on the right source file name?You cannot write the name in the recipe, because the name is different each time the implicit rule is Projects ¶. #file Makefile include ${MY_RUN_DIR}/common. o b. – MadScientist. Keep your variable names always clear and meaningful. Make will expand the argument to undefine so if the variable ENV_VAR_TEST is set to the How do I properly set an undefined ENV var in the Makefile through shell script logic? Everything seems to work when the ENV var is already defined in the environment Once you're inside the recipe for the makefile it's all shell commands. Then on the command line, make VAR="bla bla" makes VAR start with "bla bla" followed by the remaining words assigned in the Makefile. Ah, of course, I need a simply expanded variable, not a recursive one. setenv-file-unset: Unset all the environment variables defined in an env file. This has nothing to do with make, by the way. You are unclear as to what is done by GNU make, and when, and what is done by the shell, and when, to execute a recipe. Hello ! I'm Xavier Jouvenot and in this small post, we are going to see how to handle user variable in a Makefile. 3 Automatic Variables. Another way is to use two different variables, say, VAR_CMDLINE and VAR_MAKE, where in and if you put this in a makefile: main: echo value is ${ABC} (except don't copy paste that because my tab is actually four spaces) and then pass it into the file like this: $ ABC=123 make main echo value is 123 value is 123 everything works as expected. I have I have GNU make 4. But the target-specific variables should have precedence over the global ones, so overriding the BUILD variable will work, since it will I am trying to define variables in a Makefile, according to conditions. The shell gets result=true or result=false depending on the value of the make variable CHECK. The best way to prove that an environment variable has been set, is to query this environment variable inside another program that make wil call. c but you have to remember that the dependencies are complete - it assumes that a. cpp:EXTENSION=cpp cpp:CC=g++ cpp:COMPILE Please help with this problem. getenv("MURDOC")) to truly query the environment variable. For example the symbols: # and $. If your goal is to have a set of environment variables defined for any user shell (I assume this means interactive shell), you can simply add these definitions to the shell's startup file (. : Macros/Variables in makefile. to CXXFLAGS but shrug. This is very complicated and probably not required for 99% of all cases. If you set an environment variable in one shell window, it doesn't affect other shell windows. VARIABLES and filtering them out. /Makefile in the project main directory, the extension should determine the file automatically, and you can see it associated with the file in the extension sidebar, under "Makefile" section. Hot Network Questions One of my colleague's largest publication seems to be plagiarized/purely reproductive-What to do? Every environment variable that make sees when it starts up is transformed into a make variable with the same name and value. evaluating a variable in Though I don't have the permissions to change the Makefile I am looking for possibility to undefine the broken? variable. NOTE: $(flavor) takes a variable name, and not its expansion. Realize that a makefile is not a shell script, and they have different syntax and rules. I have a question concerning a line in a Makefile. env syntax is not a subset of the Makefile syntax because there are certain symbols allowed in . or You signed in with another tab or window. See Communicating Variables to a Sub-make. Define a variable, overriding any previous definition, even one from the command line. Attempting to use an unset variable will typically result in errors, interrupting your workflow. If you specify a value in this way, all ordinary assignments of the same variable in the makefile are ignored; we say they have been overridden by the command line argument. Ref: The Gnu Make manual - Special Variables Note: I said 'Makefile normally is not parsed a second time'. To unset an environment variable, use the unset command with the following syntax $ unset <variable> Given the examples cited above, you would run those commands $ unset USERNAME $ printenv USERNAME <nothing> Using the set -n command. It fundamentally misunderstands make: makefile is not a procedural language and targets are not functions that can be called (the closest you can come is, as you suggest, recursively invoking make). First, in your script, do: UNAME=uname Then, in order to put this in your Makefile, start out with Makefile. MAKEFILE_LIST. The rules for expansion and testing of variable-name are identical to the ifdef directive. in" and the second creates a variable called VAR that will be used in the subsequent lines. , coverage:) and set the variable without it. Also you need to use $$ to refer to shell's $. I've tried replacing the @ sign with $@, as basically what the substitution reference is supposed to do is to simply replace the suffix of the target from . STATIC_LIB = TRUE all: makelib $(var) makelib: ifeq (${STATIC_LIB}, TRUE) var=staticlib else var=sharedlib endif Variables specified on make command line override the values assigned in makefile: TMPDIR := "/tmp" test: @echo $(TMPDIR) And then: make TMPDIR=whatever whatever It is generally considered a bad practice for makefiles to depend on environment variables because that may lead to non-reproducible builds. The default value of . The LLVM Makefile System is quite generous. Basically the variable is assigned when the variable is defined, which is preventing you to do what you want. First, the reason why it does not work : You're using target-specific variables, but those are only available in the context of a target recipe (I'm quoting the manual here), not during the rules evaluation : Make will first read your Makefile, evaluate your $(OBJDIR) and $(TARGET) rules (at this point $(TARGETDIR)is not yet defined) then, it will try to update all, and at this sets ‘frobozz’ to ‘no’. – Peter Krauss. A variable is a name defined in a makefile to represent a string of text, called the variable’s value. An argument that contains ‘=’ specifies the value of a variable: ‘v=x’ sets the value of the variable v to x. For eg. Follow edited May 11, 2016 at 17:34. Because the Makefile is not executed further. However, you don't really need to do this. Each Provide a default value for the internationalization variables that are unset or null. d to . I don't think that's a problem. Just combine the commands in one line, separated by commas, use double dollars; if the line is long, escape the new lines. If this variable is not set in your makefile, the program /bin/sh is used as the shell. A variable is a name defined in a makefile to represent a string of text, called the variable's value. in which should have something like. Peter Mortensen. PHONY: all all: echo $(MYVAR) This is not really equivalent to the code in the question. Currently it looks like this where it seems that the BUILD_ROOT variable has been known to be unset. export. Tell make to export all variables to child processes by default. I tried this: gulp:=. – vinni_f. Building software that uses LLVM does There is a single "configuration" makefile, which contains some logic which, among others, sets up target directories in the form of make variables. How can I achieve this? I need this, as I invoke make inside a shell script and the value required by the makefile can be passed from the shell as $1. You can even unset this variable in the middle of the Makefile, causing the next target in the file to become the default target. Since the original Makefile was written as a stand-alone script, it will unknowningly (re)define the usual suspects (CC, AR/RANLIB, etc. Set or unset environment variables from an "env" or dotenv file. This special significance of ‘$’ is why you must write ‘$$’ to have the effect of a single dollar sign in a file name or recipe. /rebar get-deps . c’ file into a ‘. When used interactively, each function prompts for a file. I have (kind of) specific use-case where I need to do these steps: run command1; assign output form command2 to env variable; run command3 which read env variable assigned in step 2; This is the makefile implementing the steps described above. Does anybody has some suggestions bash For instance, if you used a make variable just because you couldn't pass a shell variable from one line of your recipe to the next (normal, they are executed by two independent shell invocations), you could reduce your recipe to a single line (but with ; \ line continuation for better readability): Lazy Set VARIABLE = value Normal setting of a variable, but any other variables mentioned with the value field are recursively expanded with their value at the point at which the variable is used, not the one it had when it was declared. SHELLFLAGS is -c normally, or -ec in POSIX-conforming mode. A description file (makefile) contains a description of the relationships between files, and the commands that need to be executed to update the targets to reflect changes in their prerequisites. If I have FOO := $(BAR), and then somewhere I'm interpolating $(FOO) into a shell script, I want $(BAR) to be expanded. In this blog post, we’ll explore different approaches to handle this scenario effectively. You can alter the values of these variables in the makefile, with arguments to make, or in the environment to alter how the implicit rules work without redefining the rules themselves. ribeqrqu oznk udisal dtmy thy dndog lyb fptnqiej tbbvux qzllq