Makefile if statement in recipe. Provide details and share your research! But avoid ….
Makefile if statement in recipe Attempting to create a makefile with a run rule which has an if in it. The only effect of $(shell ) is that it expands before any recipe is run. ifeq ($(TEST_FLAG)$(DEBUG_FLAG),TRUEFALSE) do something endif It's also possible to use the Conditional functions, which are more likely to be useful in a loop (as ifeq will probably not do what you expect in a loop, it will be tested exactly once). I changed eval to info and got this: @mkdir -p $(dir a) @printf "%-5s b\n" c Run So I thought maybe my explicit tabs in the macro definition were causing trouble, so I removed them and tried again: # make Makefile:7: *** missing separator. make by default runs the recipe if the target is missing or outdated (a missing file in this context may be viewed as an infinitely old file You didn't specify what compiler(s) you are using, but if you have access to gcc/g++ you can use the -MM option. Conditionals can compare the value of one variable to another, or the value of a variable to a constant string. But before any of those things can be done, you have to expand the $(eval ) function, and the expansion of the $(eval ) function, like expansion of This is a solution I have used to time the execution of makefile build items (recipes, and their respective items, and moreover even the output of the items). Additionally, if the ls` commands generates a non-zero exit status, the actions stop anyway, so the extra testing shown is spurious (unnecessary, shall we say). Some system have installed colorgcc script. Line $(info aaa) prints aaa fine. The make program does not try to understand shell syntax: it performs only a very few specific translations on the content of the recipe before handing it to the shell. If the condition is true, make reads the lines of the text-if-true as part of the makefile; if the condition is false, make ignores those lines I have a Makefile which creates build a programme called monitor: fo/monitor: fo/monitor. A few options you can pass to make:-n: echos commands that would be run, but without running them. 2013-07-10 -c is not a portable option to stat, so I'm guessing that you are using it to determine A number of build systems from the autotools to the kernel build system to CMake, etc. As in normal makefile syntax, a single logical recipe line can be split into multiple physical lines in the makefile by placing a backslash before each newline. But you can set variables outside the rules: just remove all of the leading TABs from your conditional statements above. Most of the makefile uses make syntax (see section Writing Makefiles are used to help decide which parts of a large program need to be recompiled. Conditionals can compare the value of one variable to another, or the value of a Conditionals can compare the value of one variable to another, or the value of a variable to a constant string. So you can just write, e. Sign up or log in. But the expansion of $(shell COMMAND) is the result of the execution of COMMAND by the shell, so using it in a recipe, instead of just COMMAND simply You're looking in the wrong place -- Make isn't complaining about that particular if statement -- Make doesn't use then's, so it wouldn't expect one. That file must be used in a subsequent recipe (if it exists). You are testing an environment variable in a shell command executed by make. Conditional Compilation in Makefile. One checks for the existence of the $(MAKECMDGOALS) special variable and the other detects whether any of the command line targets matched those listed in a variable (NODEPS). 65 # make Makefile:7: *** recipe commences before first target. Make will (1) parse the entire makefile (and any included files) and build an internal graph of all the prerequisites, than (2) run recipes for targets that are outdated. By indenting it with a TAB, you have put it into the recipe, and all commands in the recipe are passed to the shell. This article provides step-by-step instructions and examples for using conditional statements in Makefiles. We have a Makefile with a recipe that invokes a script to generate a C header that is then included into many other source files: gen-header. On the contrary, it looks only natural to move the script directly inside the recipe. This means the first thing in the makefile seems to be part of a recipe: it begins with a recipe prefix character and doesn't appear to be a legal make directive (such as a variable assignment). On the contrary, it looks only natural to move the script directly Given the following Makefile fragment: TOOLS=foo bar define TOOL_install install -c $(1) $$(prefix)/bin/$(1) endef . Also prints the makefile name and line number where the recipe was The title is somehow confusing, because make takes the first target if not specified differently (e. Basic if else statement in Makefile; In case of a typical run target write a wrapper shell script around the makefile which lets the makefile rebuild the target and then run the target. You can either set a value explicitly in the makefile or I have the following code in MAKEFILE, using this , I want to print info in accordance with whether a flag is set or not. Users use many different shell programs, If statement Makefile tcsh. PHONY: all all: job1 job2 job3 . But from there, you cannot set a 3. out 2 . The correct usage of the Makefile is one of the below. So it still does not quite work. In general I strongly discourage anyone from The trick with makefile syntax is that when a line after a target begins with a tab character, this lines is not a make statement anymore, but rather is passed (after $ variables How to add a dependency in makefile only if a recipe (or another dependency) fails? Ask Question Asked 10 years, 10 months ago. Making statements based on opinion; back them up with references or personal experience. when the user provide a version Trying to find simple way of printing information in makefile. $ make FOO=yes one Apparently the variable assignment in the else is breaking things when the else 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 Pertinent to your question, each logical line in a recipe is run in a separate shell. What I do is create a file with the extension of . Conditionals affect which lines of the makefile make uses. Each command executes in its own subshell; a variable set in one command cannot be used in another. Try the -i flag (or --ignore-errors). I am having trouble with removing directories. By the time the eval is run, the if statement is already evaluated and make_temp: makefile. This: foo. To learn more, see our tips on writing great Consider having a makefile, which can generate some files using generating lines listed in a file. Sign up using Google GNU Makefile treating each recipe line as sub-shell command without continuation character. The two latter methods, check if the variable was defined rather than if its value target: recipe command lines should create file named target There are some exceptions to this rule of thumb. Conditionals control what make actually “sees” in the makefile, so they cannot In this tutorial, we took a step-by-step approach to learn about the conditional variable assignment in a Makefile. The simplest method would be just to use the exit status of the test command: Another thing you should keep in mind - the make does not use bash (or ksh, zsh, any-other-sh) to process recipes (or shell function). One of the few ways in which make does interpret recipes is checking for a backslash just before the newline. Viewed 1k times Making statements based on opinion; back them up with references or personal experience. Conditionals control what make actually “sees” in the makefile, so they cannot Learn how to use the if and else statement in a Makefile to control the flow of your build process. There's a lot wrong here. Since But running make on that Makefile seems to fail because (I think) make is interpreting the leading tab to mean a recipe. For example, the A conditional directive causes part of a makefile to be obeyed or ignored depending on the values of variables. This is the section of my Makefile which fails b2dsetup: @$(ECHO) "Goes in b2dsetup"; \ @if [-d "/external/src/Box2D"]; \ @then $(PRINTF) "Option1"; \ It seems you've indented the variable assignment with a TAB character. If the file MyFile really exists, everything is ok. Conditional statements using Make. The if, and and or conditional functions consider that the empty string TAB should only ever be used to introduce a shell command, in a recipe. But my Makefile don't work correctly - in system, that haven't colorgcc, make always set $(CC) as colorgcc. Thus, PATCH_PRESENT is not equal to 0 at parse time, and make will expand the else portion of the clause. Sign I have a makefile which produces an executable from several object files and I include a version number in each object file as it is compiled. Stop. Makefiles are not executed line by line, Each line of the recipe is executed in a separate shell; the status from the ls command isn't available to the next line unless you use ; ` to extend the recipe over multiple Conditionals affect which lines of the makefile make uses. Make is simply passing those recipes to another program (the shell) and the other program is interpreting those commands. Since you haven't provided the entire makefile, or at least the section of the makefile before/after this, we can't say more than that. 1 Recipe Syntax. However I disagree that the code looks "ugly"; in fact it's extremely misleading to indent makefile statements to the same level as recipe lines; it implies they are shell commands when clearly they are not. PHONY ? Here is an Setting a variable refers to defining a variable with an initial value as well as changing its value later in the program. See Recipe Execution. ONESHELL target. b; executes the recipe with target ($@) set to one. Or, it can run the entire recipe in a single shell due to . My specific use case: I have spell-checking as part of my build process. out 1 . Make can only either run each line one command of the recipe at a time, in which case when you use -n it will not run "normal" commands but will run "recursive make commands", as in my example above. If I tap this command . Example: Makefile. I am using makefile to build my program in multiple system. I think there's an XY Makefile 3. Sign TAB should only ever be used to introduce a shell command, in a recipe. Variants of this question come up a lot. It is As a special feature to allow more straightforward conversion of makefiles to use . Then shell should not know makefile function. It's very confusing and hard to read and work with. Modified 10 years, Making statements based on opinion; back them up with It's the crux of Makefiles, The export directive takes a variable and sets it the environment for all shell commands in all the recipes: shell_env_var=Shell env var, created inside of Make export shell Run this example with make -i to The commands will be echoed to stdout by default, unless you disabled that by prefixing them with @. exa Makefiles can contain shell scripts, but only in the context of a recipe of a rule. Shell commands can only appear within a target recipe, and nowhere else. To learn more, see our tips on writing great answers. The trouble is that each line in a recipe runs in its own subshell, so the entire conditional must be in one line or it won't work. Shouldn't it be ignored as long "$(LIBBIN)" is not in . – Conditionals can compare the value of one variable to another, or the value of a variable to a constant string. , by using . Question: Can this syntax work if the conditional test is for something different on each 'else ifeq' ??? somevariable1 will be assigned during interpreting the makefile, before executing any recipe. b from the pattern %: %. This works for me: $ cat Makefile ifeq ($(INTEGRATION),false) PRODUCTION_URL="production" else PRODUCTION_URL="integration" endif help: echo "prod url ${PRODUCTION_URL}"; $ make in makefile i am using an awk script to do some text manipulation $(phony xyz): awk 'some script' file1 file2 > output; while doing this if any of the file1 or file2 is missing, it will g You cannot use target-specific variables in ifeq conditional statements. Sign Makefiles are not scripting languages. To get a message like what you want you would use something like this: It looks to me like Makefile rules can be roughly classified into "positive" and "negative" ones: "positive" rules create missing or update outdated files, while "negative" ones remove files. . Also, the eval will be expanded before the first line is passed to the shell, so it's a bit misleading to bury it in the middle of the recipe. All the "normal" parts of the makefile are in the makefile syntax described in the make manual. If statement in makefile. Get exit code 1 on Makefile if statement. out 3 That's not an answer to the question how to set a Makefile variable if it isn't set. It should never be used to indent normal makefile lines. It's passed to the shell, which is a subprocess and (in UNIX/POSIX) there's no way for a subprocess to modify its parent. One of those tools sometimes spits out an extra file. Makefile conditional rules execution. One checks for the existence of the $(MAKECMDGOALS) special Prints the entire recipe to be executed, even for recipes that are normally silent (due to '. Conditional statements are parsed by make during its first pass when it reads in makefiles. ) into the middle of recipes. This means your rule here: clean: if [ -f . The "recipe prefix character" is TAB by default. At the bottom is shown my simple makefile. (I think this could very well be that my vim rules $ make Makefile:7: *** recipe commences before first target. a %. The other will be assigned as the recipes are processed. I need to add a rule where a recipe sets a variable to a value and calls another recipe. o $(EXEC) fresh : | clean clearscr all clearscr: clear EDIT Dec 5. I am trying to loop through the . An if The if function provides support for conditional expansion in a functional context (as opposed to the GNU make makefile conditionals such as ifeq (see Syntax of Conditionals). 0. You cannot trigger a make rule by executing the name of its target as a shell command. /bin/status ]; then rm -f . d files for . PHONY: deploy hello deploy: rsync . Target-specific variables are not defined until the second pass, when make is actually building targets and running recipes. ifeq ($(SET_FLAG),) $(info *****not set*****) else 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. Or to be more specific, the make reads its own SHELL variable (which is usually /bin/sh). I am trying to use if and else statement in a Makefile but all the things I tried down below are not working. I want to keep VERBOSE=1 available because we have some scripts that make use of it (and use other makefiles only aware of VERBOSE). In the vast majority of cases, C or C++ files are compiled. Provide details and share your research! But avoid . out). Makefiles are really two completely different languages combined into a single file. /bin/status fi From the docs: "If the . Asking for help, clarification, or responding to other answers. Using ifeq with multiple options. The recipe is expanded once in its entirety. Conditionals can compare the value of one variable to another, or the value of a My example is meant to appear outside of any recipe, as makefile syntax not shell syntax. You can use spaces before ifeq or other Makefile statements. It will work, in some situations, but it is very brittle and can break easily. Your attempt doesn't work because pattern rules with multiple targets and explicit rules with multiple targets are treated quite differently. PHONY : clearscr fresh clean all all : compile executable clean : rm -f *. STATUS := $(if $(strip $(shell pacman -Qq zsh | awk Conditionals can compare the value of one variable to another, or the value of a variable to a constant string. The trick is to dynamically control whether the silencing @ is present on the recipe lines or not and if it is to replace it with a manual echo of some friendlier message. Makefiles have the unusual property that there are really two distinct syntaxes in one file. Second, you have a useless recursion here. However, it is difficult to read lines which are too long to display without wrapping or scrolling. For example, clean: -rm -f *. The problem is detecting recipe change, if thinking about it, as makefile. Assuming make is GNU Make, all the environment variable settings inherited by make are automatically registered as make variable settings. Load 7 more related questions Show fewer related questions 5 Writing Recipes in Rules. So the result Conditionals affect which lines of the makefile make uses. It follows that syntactic units of the makefile, such as rules, may safely be split across the beginning or the end of the conditional. In other words, there can be only one rule with a recipe for a given target, but there can be as many rules without recipes for the same target as you like. [] So what is happening here is: checks the dependencies for one: finds one. a (the one that triggered the rule); For example, I don't know what the shell if-statement you show in your question is for or how it relates to the rest of your question. Use the eval function to generate the rules. I believe this is possible @Matthias009 when I test GNU Make v4. To ignore errors in a command line, write a -at the beginning of the line's text (after the initial tab). 82. And when make will pass the recipe to the shell it will first expand $(@D) which, this time, has a value: bar. d files. recipe commences before first target. Existing questions on SO only work on the highest level in the Makefile. 1 Splitting Long Lines. Also, the -u option is a POSIX From the docs: "If the . You must understand that a Makefile is not like a shell script. GNU make has no limit on the length of a statement line, up to the amount of memory in your computer. Makefile Conditionals directives. To learn more, the recipe does not, in fact, create any of the rule's designated targets; instead, it attempts to link the object files (see next) together into an executable, assigning the default name to the result (perhaps a. If the condition is true, make reads the lines of the text-if-true as part of the makefile; if the condition is false, make ignores those lines completely. print: ifeq ("minikube", $(env)) @echo "yes" else @echo "no" endif Execution from shell $ make print env=minikube no. o: biz. If you're lucky, then an attempt to do so will have exactly the kind of failure you describe. Content that is NOT IN A RECIPE is always evaluated during the first step. If you have a sufficiently new version of GNU I have the following code in MAKEFILE, using this , I want to print info in accordance with whether a flag is set or not. Note that since you don't have the newlines in the shell anymore, you may need to add a semicolon at before the backslash newline for some commands, e. We first understood the basics of using variables in a Now I know I can simply put a bash if expression in the make file but I would like to use the make files own condition. Modified 10 years, 10 months ago. b; finds one pattern rule for both one. How to do a conditional statement in makefile. If either of those two files are out of date, the recipe should run, once. 2. Makefile (1) ifdef myvar MYVAR := $(myvar) else MYVAR := default endif . Makefiles use a “line-based” syntax in which the newline character is special and marks the end of a statement. I want the recipe to succeed if its command returns 1, and fail in all other cases. Could anyone please help to give me some comments? Ok, I use below statements; but still can't create tmp Note I use $$(id -u) not $(shell id --user); the recipe is run in the shell already and it's an anti-pattern to use the make shell function in a recipe. GNU make has no limit on the length of a statement My Makefile is very simple: all: [ -f MyFile ] && echo "MyFile exists" Of course the recipe line begins with tab. The problem I'm having is that none of the branches within my conditionals get The $(eval) will be parsed just as make is expanding the recipe. Thus, you can't change the behavior of make, including setting make variables, from within a recipe: that recipe is Each line of a makefile is run in a separate shell. I can use ! to invert the status, but I would like to fail when recipe returns 2 as well as 0. 1 Splitting Recipe Lines. o This causes rm to continue even if it is You can use ifeq with a concatenation of your values, eg. When is that command going to be executed? There is no target that would trigger that command. h # GMake and GCC rules to produce and include . ONESHELL, any recipe line control characters ('@', '+', or '-') will be removed from the second and That's not an answer to the question how to set a Makefile variable if it isn't set. GLOBAL_VAR_A := global_var_a all: $(eval RECIPE_VAR_A=recipe_var_a) ifdef RECIPE_VAR_A @echo $(RECIPE_VAR_A) for RECIPE_VAR_A else @echo RECIPE_VAR_A is defined only within the recipe endif ifdef GLOBAL_VAR_A @echo GLOBAL_VAR_A is defined globally @echo $(RECIPE_VAR_A) for What is the difference between an ifeq directive in GNU Make and the if function? When should I use each? Are they different because ifeq is parsed by a "pre-processor" in GNU Make? I'm trying to get the exit code on the ifdef statement if the statement is not true, but I tried by using exit 1 and $(call exit 1) when using the first on the following code I get "Makefile:11: * Skip to main content. $ make Makefile:4: Extraneous text after `else' directive Makefile:6: *** commands commence before first target. /a. Executing It's critical to understand that the lines of the makefile which are NOT part of a recipe (generally, not indented with a TAB) are parsed by make, and the lines of the makefile Without the recipe, one can populate the list of prerequisites anywhere in the makefile, a target can occur in the left hand side of multiple rule statements. Makefile: process colon-separated environment variables According to the doc, in the recipe part, the code after a tab is send to shell. It surprises me somewhat that an empty rule doesn't force the makefile to be reread. The -is discarded before the command is passed to the shell for execution. Any ideas what could be going wrong? There is no grep I'm looking for a Makefile which is more user friendly in a test environment. 2013-07-10 -c is not a portable option to stat, so I'm guessing that you are using it to determine 1) Each command in a makefile recipe runs in its own subshell. o: bar. I want it to execute ONLY IF the filename ${MFN_LSTF} exists. But if this fil The following is a simple recipe that is not behaving as I want it to: $(eval PkgName := $(shell pacman -Qq zsh | awk '{print $$1}')) $(if ifeq ($(strip ${PkgName}),), pacman -Sy --noconfirm zsh) A A Makefile deploy recipe needs an environment variable ENV to be set to properly execute itself, whereas other recipes don't care, e. Setting a variable in an if statement in Makefile? Hot Network Questions How to do a conditional statement in makefile. I've tried using the traditional ifeq makefile statement, but that doesn't appear to i'm having trouble understanding why Make will run the "lib"-recipe even if the file already exists. It will not be parsed if the recipe is never invoked. This article provides step-by-step instructions and examples for using Makefile has four conditional statements: ifeq (two values are equal), ifneq (two values are not equal), ifdef (value is defined), and ifndef (value is not defined). If the condition is true, make reads the lines of the text-if-true as part of the makefile; if the condition is false, make ignores those lines To be fair eval is probably the most advanced topic described in the GNU make manual: understanding it requires reading and understanding a significant portion of the rest of Other parts of the makefile can be indented by spaces, or not at all -- make doesn't care there. Recipe Example: Changing Application. 0 I want to make a shell script to run a Makefile. make CATEGORY=parser TEST=basic. DEFAULT_GOAL or by passing the target name as an argument of The only effect of $(shell ) is that it expands before any recipe is run. I'd like to enable a verbose compilation in my makefile, but I can't figure out how to make a conditional OR. I am trying to port a Makefile to Windows (using GNU Make). Ask Question Asked 6 years, 6 months ago. /run. All is operating well until I hit an if statement. Conditionals. The recipe is only expanded when make needs to pass some commands to the shell. It's a side-effect of expanding the recipe. c (cd fo ; $(MAKE) monitor) I have two types of system that I can run my ifeq is a make directive. Each execution is run in a new instance of the shell. Generate the whole rule with its recipe into a file destined to be included from the Makefile. min > $(shell if exist make_temp del make_temp) > $(foreach obj,$(OBJ_LIST),$(shell echo $(obj) >> make_temp)) If I don't put the if statement in a shell it is executed after the foreach loop is executed for unknown reasons so the file gets deleted. The shell has no idea what an ifeq Makefile:6: *** recipe commences before first target. I can't assume it exists in the dependencies, but I must use add it to the subsequent recipe command if it is there. – 5. It is not a big deal to run more than one makefile instance since each command inside the task will be a sub-shell anyways. To learn Since the functions don’t share any state, the only way to pass data between them is through writing and reading files. The two latter 5. However, I want the version number to be incremented only when a particular object file is created (ptarget below, the one containing main). Let me explain: I want to be able to specify a verbose compilation either by setting V=1 or VERBOSE=1. I need to modify a Makefile so some rules call different utilities depending on a variable. When I run the command make run it returns this error: /bin/sh: 1: Syntax error: end of file unexpected (expecting "then") The name of the file is Makefile. So something like this: file1 file2 : deps make_files Note that the make_files command always produces both files, and its invocation does not depend on the target (i. I found this question (Delete a directory and its files using command line but don't t 5. Editing the makefile as per suggestion from @MadScientist (i. h foo. PHONY: install install: all $(foreach tool,$(TOOLS),$(eval $(call Foreach template in makefile recipe. o: foo. /cub3D maps/1. The recipe for a make rule is a sequence of shell commands. Conditional Makefile. make fclean if [$1 == "bonus"]; then echo "make bonus" else echo "make" fi make clean . Your ifeq will be evaluated when the makefile is first read (as opposed to when the recipe is run). So, you cannot set a shell variable in one logical line, then use the results in another one. make sends each command line to a separate shell using: /bin/sh -ce "cmdline". all: STUFF="nothing" ifeq (true, true) echo "setting" STUFF="hi" endif echo $(STUFF) I have a recipe in my Makefile that returns 0, 1 or 2. Also each logical line of the recipe is run in a different shell. I try This script but every time the command make apply. What there can be is expansion of the $(eval ) function inside a recipe, and an $(eval ) function will parse makefile syntax which can do many things including set a makefile variable. It is a QA check to make sure user sets the env. That means that line is considered part of the recipe for the previous target. You're looking in the wrong place -- Make isn't complaining about that particular if statement -- Make doesn't use then's, so it wouldn't expect one. To learn more, see our tips on writing great Hence the makefile becomes. The recipe references an undefined variable $(PACKET_OBJECT). i used the following code, but it seems not working: DIR= Sources \ Sources_2 @for entry in ${DIR} ; Learn how to use the if and else statement in a Makefile to control the flow of your build process. eval is like any other make function or variable and obeys the same rules for when it's expanded as any other variable or function: if it appears in a recipe context it will be expanded if, and only if, that recipe is invoked. But every time I get an unexpected result. It should never be used to indent normal Without the recipe, one can populate the list of prerequisites anywhere in the makefile, a target can occur in the left hand side of multiple rule statements. ONESHELL special target appears anywhere in the makefile then all recipe lines for each target will be provided to a single invocation of the shell" (emphasis mine). Users use many different shell programs, but recipes in makefiles are always interpreted by /bin/sh unless the makefile specifies otherwise. The best I've been able to do so far is Moving the aaa = 1 fixes it because the . This will also echo commands that are prefixed with @ I've written a fairly simple test Makefile where I define two targets, all & clean. Sign In this very simple makefile, I try to set a variable inside a condition, but outside the change is not noticed. I've got two different conditional statements. The recipe of a rule consists of one or more shell command lines to be executed, one at a time, in the order they appear. Makefile has four conditional statements: ifeq (two values are equal), ifneq (two values are not equal), ifdef (value is defined), and ifndef (value is not defined). How to add a dependency in makefile only if a recipe (or another dependency) fails? Ask Question Asked 10 years, 10 months ago. Example of a Conditional; Syntax of Conditionals; Conditionals that Test Flags i'm having trouble understanding why Make will run the "lib"-recipe even if the file already exists. Then the recipe is empty and so make doesn't actually run any commands. py $(INPUT) -o gen-header. Well, that will definitely do it. -means ignore the exit status of the command that is executed (normally, a non-zero exit status would stop that part of the build). The if function provides support for conditional expansion in a functional context (as opposed to the GNU make makefile conditionals such as ifeq (see section Syntax of Conditionals). It should look something like this: VARIABLE=true define test_ifeq $(eval FOO := $(if $(filter A rule without a recipe simply adds any provided prerequisites to the given target. Recipe Syntax; Recipe Echoing THE major reason to use make IMHO is the -j flag. My Makefile is very simple: all: [ -f MyFile ] && echo "MyFile exists" Of course the recipe line begins with tab. Other languages typically have their own For your use case you can define a make variable $(STATUS) and check within the if statement the absence of install. For example a: <tab>$(info ===) if I run make a, it outputs In effect it is like a case statement testing one variable against multiple possible values. So running exit just exits that sub-shell--not the makefile as a whole. I can think of two options: Simply remove the $ Making statements No, there is no and operator for the conditionals (but there is a and function that can be used in conditionals). However, recipes are meant to be interpreted by the shell and so they are written using shell syntax. In makefile when I use inside bash function The recipe is executed only once to make all the targets. 4. However, a You're trying to get the shell stuff in a recipe to conditionally invoke makefile stuff, which doesn't work, as you've found. Hot Network Questions Birational K3 surfaces Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. GNU Make provides special target ONESHELL: that makes all commands for any recipe to run in the same shell, which allows variables to be written to in one command and expanded in another. By default, make execution will stop if any sub-shell returns an unsuccessful exit status (by convention, 0 means success, so anything else will halt execution). make -j5 will run 5 shell commands at once. variable to a value within a range/list. Basically, you want make to see something like:. Here's how I currently handle it: I'm having a problem with conditional statements in make. g. cpp file, and then "include" the . – Colin D Bennett. PHONY: all all: echo $(MYVAR) The ifeq and the likes are evaluated at the moment when make reads the makefile, that means there is no actual ifeq present in the assigned value of your test_ifeq variable. This is a part Most of the makefile uses make syntax (see Writing Makefiles). $(ENV). Is there a way using gnu make to do this? I want to do this outside any recipe, before make starts building any targets. 1. First, you should never use make to run make recursively, always use $(MAKE). What can I do? (I created this Makefile with Vim editor and the format of Vim is already set to unix). SILENT' or '@'). Multiple if statements in makefile conditionals. 9. 1, using ifdef or ifndef (as in the accepted answer) only works if the variable being evaluated is immediately set (:=) instead of lazily set (=). You should post how you are I've written a fairly simple test Makefile where I define two targets, all & clean. So, the syntax you use to write recipes is the same as you'd use to write a shell script (or write shell commands at your shell prompt). a and one. sh, the command make will apply. 2. PHONY: job2 job2: ; . However, according to the mechanism of make, it should invoke the recipe for If you don't indent ifeq it will be evaluated when the makefile is read. Basic if else statement in Makefile. Can make do it in some easy way? – Pavel Kunyavskiy. If the same file is a prerequisite of multiple targets, and each of those targets has a different value for the same target-specific variable, then the first target to be built will cause that prerequisite to be built and the prerequisite will inherit the target-specific value from the first In my makefile I have a recipe that produces two files. You define AVAR in the first command (the "if" statement), so it's not available to the second command (@echo $(AVAR)). Ask Question Asked 10 years, 6 months ago. (I think this could very well be that my vim rules are set not quite right: presumably, it should only indent-with-tab if the preceding line is a rule, not a global condition) Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. To achieve what you need you have to use $(if ) and $(filter ) built in functions along with $(eval ). On terminal: setenv ENV_PARAM x In Makefile: PARAMS := a b c if ${ENV_PARAM} exists in $(PARAMS) true else false endif I have a makefile that runs some custom tools. Commented Nov 8, Making statements based on opinion; I am writing a makefile, and my shell is zsh. , we don't use the target name or any stem in its invocation). For example, the first thing in a makefile before any targets are defined, and not part of If the line begins with a tab, it will be considered part of a recipe for a rule. 1. The else directive causes the following lines to be obeyed if the previous A conditional causes part of a makefile to be obeyed or ignored depending on the values of variables. I tried to do this using a conditional statement in the recipe: Make every target depend on a file that contains the content of the recipe. You need to have backslashes at the end of each (but the last) command line. The problem that I've encountered with is that, the foreach statement executes always. – Making statements based on opinion; back them up with references or personal experience. I need something like: foo-a: $(eval MY_VAR=a) goto foo recipe foo-b: $(eval MY_VAR=b) goto foo recipe foo: Do something that uses MY_VAR Docs: "Be aware that a given prerequisite will only be built once per invocation of make, at most. Each line of the recipe is executed in a separate shell; the status from the ls command isn't available to the next line unless you use ; ` to extend the recipe over multiple lines. I'm trying to setup a Makefile that will search and copy some files (if-else condition) and I can't figure out what exactly is wrong with it? (thou I'm pretty sure it's because a combination of spaces/tabs written in the wrong place). An explicit rule with multiple targets creates multiple explicit rules, one for each target. Make doesn't read the makefile and run each rule as it's read. This is good if you have 4 CPUs say, and a good test of any makefile. But if this 5 Writing Recipes in Rules. You I need to add a rule where a recipe sets a variable to a value and calls another recipe. @Pat: I rather prefer this approach where I can separate the assignment in one place in the Makefile, possibly comparing against more values using ifeq/else ifeq/else, rather THE major reason to use make IMHO is the -j flag. So, taking your original makefile, let's assume that you have asked make to build ${DEF_TARGET}. ifeq ($(SET_FLAG),) $(info *****not set*****) else $(info *****set *****) endif Making statements based on opinion; back them up with references or personal experience. eval is like any other make function or variable and obeys the same rules for when it's I'm new to Makefiles so please bear with me. ONESHELL, in which case when you use -n it will either run the entire recipe as a My intent with this code is to use the same makefile for different directories which have the same file name, but with a different prefix. properties (YAML) Values in a Spring Boot 3 Application; Struggling to Deploy Firebase Function This a Makefile: all: ifeq (0,0) echo hello endif Note: there is a tab before if, echo, and endif. I can think of two options: Simply remove the $ Making statements More about "if statement makefile recipes" IF STATEMENT IN MAKEFILE - STACK OVERFLOW. Extra spaces are allowed and ignored at the beginning of the conditional directive line, but a tab is somevariable1 will be assigned during interpreting the makefile, before executing any recipe. What I tried. makefile conditional. But from there, you cannot set a variable that applies elsewhere in the Makefile. target: if true; \ then \ echo true;\ fi 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 If by configure release/build, you mean you only need one config per makefile, then it is simply a matter and decoupling CC and CFLAGS: CFLAGS=-DDEBUG #CFLAGS=-O2 -DNDEBUG CC=g++ -g3 -gdwarf2 $(CFLAGS) Depending on whether you can use gnu makefile, you can use conditional to make this a bit fancier, and control it from the command line: Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company Recipes are expanded by make before they are passed to the shell because, for instance, it's the only way to replace the automatic variables ($@, $<, $^) and other variables ($(CC), $(CFLAGS)) by their values. PHONY: job1 job1: ; . ONESHELL feature doesn't actually take effect until make starts to read the NEXT command; until that happens make is trying to read a recipe for the . But you never try to make use of that. Your statement this happens when the makefile is parsed, before the recipe is run is not true. Modified 6 years, so I really wonder if I have to use sh or tcsh if statement syntax here ? The correct Your statement this happens when the makefile is parsed, before the recipe is run is not true. Well, file happens outside the purview of the "run a recipe" engine. c files in a specific directory through the makefile. That's why you need the backslash. For example, the following is equivalent to the example above (well, assuming that the Makefile is properly designed so that the order of prerequisites does not matter): I like this style and this syntax works as written in the version of gnu make I am using. Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. See 6. a space after the ifeq): The most fundamental aspect of writing makefiles to understand is the difference between the makefile syntax and the recipe syntax. You need to escape dollar signs in makefiles by using an extra dollar sign. I'm trying to add a conditional statement to my makefile to select a set of configuration files based on an input variable and process them using an external bash script Makefile target "scripts" are not run like real scripts, instead each command is run in a separate shell. – The ifndef is expanded when the makefile is first being read, and the eval is expanded when the recipe is run. PHONY: job3 job3: ; . Right now, a rule looks like: ci: [shell I have a recipe in a Makefile which should always be executed, without any condition and no matter what (and if a) target is specified at the invocation of make. As long as the condition is static (doesn't rely on the specific recipe or order in which the makefile is read) But running make on that Makefile seems to fail because (I think) make is interpreting the leading tab to mean a recipe. , ENV = . Thus, shell variables that are set on one line of a recipe will have no effect on the next line. sometimes, a directory might contain multiple versions of the file with a different prefix and i want to define a hierarchy of those prefixes (defined by LIST in my example). Conditionals control what make actually “sees” in the makefile, so they cannot be used to control recipes at the time of execution. A make recipe is not makefile syntax, it's a shell script. I've tried this also: 3. See the GNU make manual where it says: Hm. do this sort of thing. Each line of the resulting expansion is then executed one-by-one. A Makefile specifies targets and what must be done to make those targets. ${MFN_LSTF} holds a filename that contains a one column list of makefile names that are assumed to be at the same local directory as this makefile recipe. The shell interpreter is the most primitive one: sh. d for every . conditional check within makefile. The eval, on the other hand, will not be executed until the recipe is run (afterwards). Using conditionals in make. – mforbes. I suppose that this is probably a misspelling of $(PACKET_OBJECTS). Conditionals control what make actually “sees” in the makefile, Every command line in make runs in its own sub-shell. Here's part of Makefile: A conditional causes part of a makefile to be obeyed or ignored depending on the values of variables. I believe this is possible since make 3. sh bonus, The Rule bonus will be applied. cub Other parts of the makefile can be indented by spaces, or not at all -- make doesn't care there. If the condition is true, make reads the lines of the text-if-true as part of the makefile; if the condition is false, make ignores those lines The lines of the makefile following the ifeq are obeyed if the two arguments match; otherwise they are ignored. c fo/inotify. The command that I putted on the terminal was: That means that they cannot be indented by a TAB character in a recipe, because everything indented by a TAB character in a recipe is assumed to be a shell command and is Each recipe for a rule is a set of one or more shell commands (POSIX sh). c files # to track header/source dependencies follow Making statements based on opinion; back A number of build systems from the autotools to the kernel build system to CMake, etc. Only a real TAB as the first character on the line could cause problems. e. I need something like: foo-a: $(eval MY_VAR=a) goto foo recipe foo-b: $(eval You're trying to get the shell stuff in a recipe to conditionally invoke makefile stuff, which doesn't work, as you've found. 10 Variables from the Environment. The documentation seems to suggest a more robust way to achieve this, by the way:. + means 'execute this command under make -n' (or 'make -t' or 'make -q') when commands are not normally executed. The trick is to dynamically control whether the silencing @ is present I have tried to remove other statements but this one, and make this Makefile, it does nothing. c or . Like this: If statement in makefile. – Hence the makefile becomes. – Thus, shell variables that are set on one line of a recipe will have no effect on the next line. Conditionally add a dependency to the targets to force them being rebuilt whenever necessary. 18 "ifeq" conditional syntax in makefile. More about "if statement makefile recipes" IF STATEMENT IN MAKEFILE - STACK OVERFLOW. c $(CC) -c -o $@ $< I trying to compare variable and string in Makefile for defining different actions depending on which value user appointed to variable from the command line. In my Makefile i want to check, if script exists and depending on it i setting up CC variable. At read time REPOSITORY_URI is undefined and so all of those commands will be expanded in your recipe, and when your recipe is run, those commands get run regardless of what you set REPOSITORY_URI to. Recipes must always be associated with a target. If you keep that in mind, the execution of a spurious command in the Makefile becomes a conceptual problem. I don't understand why you want to do this outside the context of a rule but the only way to do it is with the shell function: If statement in makefile. h: $(INPUT) script. PHONY ? Here is an extract from the Makefile in question (ts=2, see "TODO"). Commented Nov 8, Making statements based on opinion; back them up with references or personal experience. You should post how you are calling the macro, as there may be something there that is causing your problem. A conditional causes part of a makefile to be obeyed or ignored depending on the values of variables. Conditionals control what make actually “sees” in the makefile, They control the behaviour of make for the tagged command lines: @ suppresses the normal 'echo' of the command that is executed. In general I strongly discourage anyone from adding conditional statements (ifeq etc. but if I wrote this . kfugirsjptirmwvsmchfotgynqsebxxcxklmqaionqphq