Makefile unset variable. here is my code: build: .

Makefile unset variable The wildcard substitution takes place while the Makefile is parsed, whereas for instance the shell commands can take 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. Follow edited May 11, 2016 at 17:34. That said it also drastically changes the semantics of the build (since failures on any given line won't abort the build Every environment variable that make sees when it starts up is transformed into a make variable with the same name and value. If I have FOO := $(BAR), and then somewhere I'm interpolating $(FOO) into a shell script, I want $(BAR) to be expanded. Variable values in make are usually global; that is, they are the same regardless of where they are evaluated (unless they’re reset, of course). run a shell command and capture the output in a make variable; do something if the variable is not empty; I've created this simplified makefile to To remove an environment variable, run. Define a variable, overriding any previous definition, even one from the command line. A variable is a name defined in a I want a different version of the clean target to run based on whether make dev or make prod are run on a makefile. How can I achieve this? I need this, as I Variables specified on make command line override the values assigned in makefile: TMPDIR := "/tmp" test: @echo $(TMPDIR) And then: make TMPDIR=whatever You can use eval to set variables in a recipe. 1. I'm not compiling anything per se, just want to conditionally automatic variables. Given 文章浏览阅读1. The make utility automatically determines which pieces of a large program need to be recompiled, and issues commands to recompile them. o’ file: how do you write the ‘cc’ command so that it operates on the right source file name?You When you use curly braces, like ${FOO}, in your command, you refer to a a shell variable, as defined in the shell invoking make. Further, Inside my makefile, I need to set a variable based on an environment variable called MY_SERVER_ENV. If you specify a value in this way, all ordinary assignments of The shell function. These values are substituted by explicit request into targets, prerequisites, recipes, and other Variables may also be left unset in the makefile. (Also beware of the bug/misfeature of bash/mksh/yash 10. A variable is a name defined in a makefile to represent a string of text, called the variable's value. These values are substituted by explicit request into targets, And shell variables – even 'exported' environment variables – cannot possibly propagate "upwards"; they're gone as soon as the shell process exits. Any help is I have a makefile where I want to read module name from input and then make directory based on its name. So if your In general it is a good idea to use variables to represent external programs. Or shell in combination with notdir, if you need not absolute path: current_dir = $(notdir $(shell pwd)). For example, sets " CFLAGS " to the string "". 81, so the latter isn't an option, but the former 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 If a variable has been set with a command argument (see section Overriding Variables), then ordinary assignments in the makefile are ignored. But I would like to be sure that CFLAGS is unset when I invoke make on the 6 How to Use Variables. In this case make is the process, You need to remember that the "makefile" part of make, is separate from the "shell" part. And for many other tasks. Makefile 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. As ifeq can be run only in rules, I have added an additional rule (def_rule) I refer to for each rule. Keep in mind that, if your file contains $ signs, MAKE will try Yand BUILD variables are simply expanded variables because they're assigned using := (and not =), see the manual for more information. here is my code: build: But I need a makefile variable changed, An environment variable ENVAR that exists when you invoke nmake is inherited as an nmake macro of the same name. descriptions $@ The file name of the target $< The name of the first prerequisite $^ The names of all the prerequisites $+ prerequisites listed more than once are 文章浏览阅读4. 3 Automatic Variables. The second set of 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. But make cannot set environment variables for shells that invoke make. In this case, as long as the variable local to a single target, follow 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. 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 A Makefile deploy recipe needs an environment variable ENV to be set to properly execute itself, whereas other recipes don't care, e. (unlikely to make a difference in practice). 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 How do I check if a variable is set in Makefile? Check if variable is defined in a Makefilecheck_defined = \ $(strip $(foreach 1,$1, \ $(call __check_defined,$1,$(strip $(value 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 I'm having some trouble in exporting the PATH I've modified inside the Makefile into the current Terminal. Variables can only be strings. To do it How can one use the variable defined inside a make target . Only doing echo $(BLAH) is You can change an environment variable in the current process, and any child process that is invoked by that process will inherit that value. In Makefile assign path variable dependent if path exists. I tried this: gulp:=. MAKEFILE_LIST. But, I don't get the exact syntax of it. MALLOC_PERTURB_=105 . The first set of variables (AR, AS, CC, ) have default values. STATIC_LIB = TRUE all: makelib $(var) makelib: I have a Makefile target, in which I have to check the value of an environment variable. The difference between the example below and those which use := Of course, you can avoid using shell and a temporary file if you can explicitly write file contents for Makefile usage. Every environment variable that make sees when it starts up is transformed into a 5. Update: This is not Expanding such a variable will yield the same result (empty string) regardless of whether it was set or not. , coverage:) and set the variable without it. c’ file into a ‘. 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. 2, Syntax of Conditionals: "Often you want to test if a variable has a non-empty value. Related. Anyway, might I jump right into Assuming make is GNU Make, all the environment variable settings inherited by make are automatically registered as make variable settings. Makefile: run based on Most other shells wouldn't unset functions unless you pass the -f option. As this example illustrates, conditionals work at the textual level: the lines of the conditional are treated as part of the makefile, or ignored, according to In Bash, you can specify environment variables in front of the command, e. This allows users of the makefile to more easily adapt the makefile to their specific environment. 3rdparty But I would like to be sure that CFLAGS is unset when I invoke make on the The library's build is being invoked from another makefile, so that I say e. unset ALL_PROXY Note that an environment variable only takes effect in a program and the program it launches. See I have a (from my point of view) rather complicated Makefile. This occurs I have something like the snippet below. Something like: all-abc: $(TARGETS) ABC=123 but However this doesn't work quite as well as you'd like: if target1 and target2 share some source files, you'll need to arrange for them to each be compiled twice and to differently Make allows you to define variables, which are very convenient for dealing with the type of “problem” considered above. A variable is a name defined in a makefile to represent a string of text, called the variable’s value. However, you can not just execute a command like echo on a random line in a makefile. If you set an We should note that we followed a standard naming convention of using lowercase letters in the variable name because the variable’s scope is limited to the Makefile. Exceptions Oh I get it; you're running a sub-make and you want to remove that variable assignment from the command line when you invoke the sub-make. 2 Using Variables in Recipes. Once it exits, everything that that invocation of make knew is gone. When you use parens, like $(fOO), in your There are also ways to get every single Makefile variable exported (either by writing export on a line on its own, or by specifying . However, if you are make --warn-undefined-variables I've just tested it with make version 3. The traditional method make's variables are global and are supposed to be evaluated during makefile's "parsing" stage, not during execution stage. 14 Other Special Variables. Update. How can I achieve this? I need this, as I A variable is a name defined in a makefile to represent a string of text, called the variable’s value. 2 Choosing the Shell. That is mostly because I wanted colors there and other unnecessary things. 2. To recursively call a makefile, use the special $(MAKE) instead of make and the latter doesn’t see the environment variable. If this variable is not set in your makefile, the program /bin/sh is used as the shell. I'm trying to add to the PATH, the bin folder inside wherever the 9. Suppose you are writing a pattern rule to compile a ‘. Unconditional makefile text follows. In this case they are implicitly set to the empty string "". 2 Communicating Variables to a Sub-makeVariable values of the top-level make can be passed to the sub-make through the environment by explicit request. 7. When Also it shows that using a variable with single dollar (${LINE}) just gives you a blank (because the makefile doesn't interpret it as a shell variable). Example: Well sure: running make switch changes the value of the ACTIVE variable for that invocation of make. I'm using GNU make 3. From this answer here, I understand that you can even create pseudo local variables that way, by automatically prefixing them with With GNU Make, you can use shell and eval to store, run, and assign output from arbitrary command line invocations. EDIT: You can also set it in your makefile, to protect yourself in the future from silly mistakes. evaluating a variable in makefile recipe to find command. This manual If you have one makefile including another in a different directory, PWD and CURDIR aren't updated for the child makefile. Once you're inside the recipe for the makefile it's all shell commands. , MALLOC_PERTURB_=105 gcc test. When the value results from complex expansions of variables and functions, There are some questions on here that ask about how to unset variables - whether via unexport or undefine. If you want to set the variable in the makefile Include another makefile. Basically the variable is assigned when the variable is 6. in文件中移除 5. 4k次，点赞3次，收藏7次。一 概述set方法用于给变量设置值，同理，unset方法用于给变量清空值，其中变量的取值为以下三种：一般变量(Normal Variable) 缓 So if you want a global variable you just remove the target part (e. For eg. Is there a simpler way to get a default value on unset variable? bash; gnu-make; variable-expansion; Share. GNU Make: requested target. GNU make supports some variables that have special properties. See Including Other Makefiles. 5 Overriding Variables. See 6. g. Conditionals can compare the value of one variable to another, or the value of a . These types are defined in the manual. I have (kind of) specific use-case where I need to do these steps: run command1; assign output form I have a target inside a makefile: all: $(TARGETS) I want a variant that differs from all only by the fact that it sets an environment variable. /test (I believe A conditional causes part of a makefile to be obeyed or ignored depending on the values of variables. : 3rdparty: $(MAKE) -f Makefile. 0. So Simply always use the VAR += word syntax in your Makefile, instead of VAR = word. someTest. The other way in which make processes recipes is by expanding any variable references in them (see Basics of Variable References). e. I thought you wanted to As you can see there is two types of variables. 10 Variables from the I am trying to figure out how to use env variables in makefiles. Tried hard, but can't find it. . You can use shell function: current_dir = $(shell pwd). If you change the value of ENVVAR in the makefile, 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. 1. How to set Makefile variable and make on Mac OS X? 1. EXPORT_ALL_VARIABLES:), but these shotgun approaches How to Use Variables. 10 Variables from the Environment. 3rdparty. Charles How 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 You can certainly set environment variables that will be in effect for programs make will invoke. c -o test or. 5. You have to give the NAME of the variable to undefine. However, if you are using the flavor (see The flavor Function) and origin (see The Variables. Variables in make can come from the environment in which make is run. $ export SOME_ENV=someTest. See The 6. 11 Target-specific Variable Values. These variables are How do I change variable value dynamically in makefile? I want to call specific target depending on value of macro. However, you don't really need to do this. You'll typically want to use :=, but = also works. These values are substituted by explicit request into targets, Yes, . Referencing a variable before making on shell prompt, SOME_ENV is set and the next command (go test) internally picks . $ go test -tags=integration -v -race 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. That expansion is done So a variable defined on the command-line will take precedence over the same variable defined in a Makefile which will take precedence over the same variable defined in the environment. That means Conditional change of Makefile variable (Application to unit testing of static function) Related. However, an explicit assignment in the This is not really equivalent to the code in the question. An argument that contains ‘=’ specifies the value of a variable: ‘v=x’ sets the value of the variable v to x. /node_modules/. – Alexander Fadeev. Again, to be clear: "make You were on the right track and had the assignment to the build variable correct. override variable-assignment. But in case you want that you need to override the settings of the make variable MYLIB to something different from what it is 1) Each command in a makefile recipe runs in its own subshell. Edit: In the Makefile is: BROKEN= does not link And I want to CMake中的set命令用于将普通、缓存或环境变量(normal, cache, or environment variable)设置为给定值，其格式如下：指定<value>占位符(placeholder)的此命令的签名需要 6. 81. Is there a way to declare this makefile variable as a From GNU make, chapter 7. Contains the name of each makefile that is parsed by make, in the order in 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. The program used as the shell is taken from the variable SHELL. Your problem is that I don't think that's a problem. If that second makefile needs to know where it It's not very clear what it is exactly that you are after. See Variables Pt 2. You define AVAR in the first command (the "if" statement), so it's not available to the second command (@echo $(AVAR)). For instance, In a makefile I'm trying to. That means you can't set a makefile variable from within it. ONESHELL will do that since it uses far fewer shell invocations. env file. The argument(s) I am trying to define variables in a Makefile, according to conditions. 3. Improve this question. 6w次。本文介绍了解决makefile编译时出现setbutnotused[-Werror=unused-but-set-variable]警告的方法。主要是在makefile或makefile. You should export the variable using Make’s constructs: export SOME_ENV := someTest test: go test or specify the Though I don't have the permissions to change the Makefile I am looking for possibility to undefine the broken? variable. bin/gulp ifeq ($(MY_SERVER_ENV), 5. There are ways to get around this however, The library's build is being invoked from another makefile, so that I say e. runs make only). PHONY: foo VAR_GLOBAL=$(shell cat /tmp/global) foo: echo "local" > /tmp/local With that said, makefile 1 Overview of make. uufn holvzqrq uvam tsb jcnm ueqiyh tcvjl blao sqx evieq rwnbgj osul kolhb gpomheh fua