Makefile shell keep newline.
I'm using GNU Make 4.
Makefile shell keep newline When in doubt, you could always debug it with -d option. The argument(s) passed to the shell are taken from the variable . Likely the problem is actually that you've incorrectly set SHELL=/usr/bin/sh in a startup file (. That Xterm has no shell. But you can define a macro that contains a newline using the define syntax: define newline It's probably easier -- and cleaner -- to use GNU Make's shell function with sed to do the replacement, rather than trying to do it entirely within make. in(depending on executables in C:\MinGW\bin). OPERANDS. It would be very bad for personal If that second makefile needs to know where it is, the following will tell you. As in normal makefile syntax, a single logical recipe line can be split into multiple physical lines in the makefile by Z-Shell - if you are using Z-Shell then the sentence will not be split up into words. 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 Beware: $(shell ) syntax is GNU Makefile extension which may not be supported by locally available make. How to get my cursor on a new line after the highlight line of OhMyPosh theme? Ask Question Asked 3 years, 8 months ago. h gcc -c $< -o $@ Here, hello. The make utility automatically determines which pieces of a large program need to be recompiled, and issues commands to recompile them. See why linebreaks in a shell variable can disappear in echo's output and learn the right way to use shell variables in commands. Currently using Makefile, I can easily call the bash script like this: dump: . Commented Jan 26, 2023 at 20:31. The problem is that the shell is taking the output of the cat and passing it to echo. The answers there explain how a different file (instead of . string. It looks hard to see how space and newlines are handled in the shell in different situations. However, it is difficult to read lines which are too long to display without wrapping or scrolling. As in normal makefile syntax, a single logical recipe line can be split into multiple physical lines in the makefile by The shell function performs the same function that backquotes perform in most shells: it does command expansion. /myTask. You can tell make to use a different shell by assigning a value to the SHELL variable (i. As in normal makefile syntax, a single logical recipe line can be split into multiple physical lines in the makefile by make spawns a new shell for each command on a line, so you cannot use true multi line shell code as you would e. For example: hello. bashrc set -m vim I just want a newline! GNU Make does its best to insulate you from the newline character. The 5. Quoting the expanded variable will fix that: echo "$var" This will preserve the newline between your line one and line two. Improve this answer. Not using the `target` directive: The `target` directive specifies the name of the file or target that you want to build. profile or . Modified 1 year ago. vimbashrc:. --keep-going should continue to the next line in the file with the exit code intact – Erik Aronesty. This is what $@ expands to. answered Mar 4, 2009 at 13:50. Update. So $? does not contain the exit status of the previous failed command, Tell Make “this Makefile is written with Bash as the shell” by adding this to the top of the Makefile: SHELL := bash With a well-known shell targeted, you can confidently skip workarounds for cross-shell compatibility, and use modern bash features. sh, test. 1 Overview of make. Given solution only works when you are running make I want to execute a Shell command but I didn't know how to do a sub bash command correctly in my Makefile import-bd: @while ! nc -z $(make ips | awk '/mysql/ { print $2 }') 3306; do \ Just replace each newline with a space-backslash-newline-tab quad using $(subst). And this is a macro which gets the args for us: Then it looks like in the 1st case the 'newline' or '\n' is converted to spaces, which seems a good idea. The -is discarded before the command is passed to the shell for execution. If this variable is not set in your makefile, the program /bin/sh is used as the shell. 10. They can nearly always be replaced by make machinery, or helper shell scripts My attempts/research. sh, deploy. From that link, note for example: You can't combine multiline constructs in a csh using semicolons. c hello. Echo will automatically convert all these characters, that's why they're being converted (see the man page for echo). In my opinion, directories should not be considered targets of your makefile, either in technical or in design sense. Either set it in the environment (export SHELL=/bin/sh) before invoking make, or put SHELL=/bin/sh on the make command line. If I have FOO := $(BAR), and then somewhere I'm interpolating $(FOO) into a shell script, I want $(BAR) to be expanded. If your shell command takes a lot of time, this difference may cause huge performance The shell function performs the same function that backquotes perform in most shells: it does command expansion. That's what $< expands to. To answer the question as asked: you can't. /script_dump. The variable $@ represents the name of the target and $< represents the first prerequisite required to create the output file. uses a more robust command to extract the target names, which hopefully prevents any false positives (and also does away with the unnecessary sh -c); does not invariably target The problem is when you split your command over multiple lines. So, if the shell expects and can interpret a quoted string, then you should use quotes. I've looked at the answers from but had no luck. However, I keep receiving "FILENAME: Not found" and destination is missing for the cp command. Get exit code 1 on Makefile if statement. NOTPARALLEL. This means that it takes as an argument a shell command and evaluates to the output of the command. Another way to set the value of a variable is to use the define directive. The main difference I came across is that mingw32-make will use windows PATH. 2 Choosing the Shell specifies this hehavrior: The program used as the shell is taken from the variable SHELL. If this variable is not set in your makefile, the program /bin/sh is used as the shell. How to properly escape recipe newlines in multi-line variable? 0. If the first operand is -n, or if any of the operands contain a Just curious, how can I preserve trailing newlines (not sure where such a thing might help) using ksh. 2 Choosing the Shell. in or simply make. The -c flag generates This causes make to continue even if rm is unable to remove a file. It would be very bad for personal 3. GNU make The shell function. How can I print a newline in a makefile? For instance, if I have a target: printIt: @echo "Compiling" How could I print out . Makefiles use a “line-based” syntax in which the newline character is special and marks the end of a statement. This manual describes GNU make, which was implemented by Richard Stallman and Roland McGrath. you can't write \n), and even the $(shell) function strips newlines from the returned value. I need to check the exit status of the tool command, and if that command fails the make has to be aborted. You need to set shell THE major reason to use make IMHO is the -j flag. This is less flexible but sometimes useful. How do I check the exit status of a Makefile shell invocation? 3. The behavior is clearly described in Subtle point #2: In the makefile it probably doesn't matter, but the distinction between wrapping with {} and makes a big difference if you sometimes want to copy the script and run it directly from a shell prompt. test -f myApp && echo File does exist Using only POSIX sh constructs, you can use parameter substitution constructs to parse one delimiter at a time. Commented Apr 17, 2013 at 8:49 @KentPawar The first method should also work in ksh. If you want a GUI based solution, install DevCPP IDE and then re-make. The first dependency is hello. That expansion is done when FOO is assigned because I used an immediate variable (:=). :. I want the cursor to be on a new line currently it is on the same line TL;DR: visit this page for a short and concise version of this article. You can use shell function: current_dir = $(shell pwd). So you cannot set Make variables there, and then use them like $(arg1) later. $(foo) will simply copy-paste a content from foo multi-line variable. (If the ‘-e’ flag is specified, then values from the environment override assignments in the makefile. This is good if you have 4 CPUs say, and a good test of any makefile. Development since Version 3. A string to be written to standard output. A variable is a name defined in a makefile to represent a string of text, except for the shell commands in rules, the right-hand sides of variable definitions using `=', and the bodies of variable definitions using the it is a good idea to break it into several lines by inserting backslash-newline at convenient places in the definition. ~/. 8 Defining Multi-Line Variables. The shell gets around this by not forking a new process when source'ing, but just running those commands in the current incarnation of the shell. So, you can format your makefiles for readability by adding newlines into the middle of a statement: you do this by escaping the internal newlines with a backslash (\) character. A rule in the makefile for the special target . Add a Once a suitable makefile exists, each time you change some source files, this simple shell command: make suffices to perform all necessary recompilations. You may also want to set -e option (aka --environments-override) on, and your environment variables will override assignments made into makefile (unless these assignments themselves use the This is not related to make; if you ran that command in your shell prompt the same thing would happen. Is there a way to embed a backslash-newline into a variable in a way that survives until it is used as a recipe? makefile; gnu-make; Share. sh 5 &' /bin/sh -c '. For example, clean: -rm -f *. If you forget to use them at some point, these special characters will be lost. So if you try to run it from git bash it won't behave quite like you expect it to (namely, it will invoke bat scripts when you don't expect it to, and shims also don't quite work). 1. make -j5 will run 5 shell commands at once. If The short answer is, you should not ever use tcsh, at least not for makefiles. I’ve also recently started using GNU make as a substitute for one-line shell scripts (so instead of a bunch of scripts like build. How to run a shell command in a makefile? To run a shell command in a makefile, use the following syntax: $(shell ) This can help to keep your makefile organized and make it easier to maintain. This is an attempt to improve on Brent Bradburn's great approach as follows:. 355k 87 87 gold badges 700 700 silver badges 696 696 bronze badges. out 3 Note: This answer has been updated to still work as of GNU make v4. make -f pax. Better shell solution when blank lines may be piped to wc. – Chris Down. SHELL := /bin/bash). e. 1. Two nits: 1. Presumably /bin/sh doesn't support the SECONDS variable. PHONY: all all: job1 job2 job3 . Since a makefile mostly contains commands to be run when building specific targets, I'd say you use just that: echo. 1 Splitting Recipe Lines. Taking it to an extreme, the following would be possible in a shell script file, because the newline acts as command-evaluation (like in a terminal hitting enter is a newline-feed that evaluates the entered command): Try the -i flag (or --ignore-errors). To use a variable from an earlier command, use a single shell. How to escape backslash in makefile shell function. The assignment of an explicit newline to a var may look odd, if that is the case, we can use: Ansi-C quoting (ksh,bash,zsh): nl=$'\n' printf (most shells): eval "$(printf "nl='\n'")" But then, those two ideas might be used directly to define the alias: 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 The only processing make does on the result, before substituting it into the surrounding text, is to convert each newline or carriage-return / newline pair to a single space. Grep exit codes in Makefile. $(dir $(realpath $(lastword $(MAKEFILE_LIST)))) Share. out 1 . The only processing make does on the result is to convert each newline (or carriage-return / newline pair) to a single space. o This causes rm to continue even if it is Every environment variable that make sees when it starts up is transformed into a make variable with the same name and value. This is because the SHELL environment variable is used to specify your personal choice of shell program for interactive use. Note the differences between Makefile variables and Shell variables in this next example. To ignore errors in a command line, write a -at the beginning of the line's text (after the initial tab). So I created this ~/. All actions in each makefile are executed with the current directory set to be the directory containing the makefile, so each makefile can be written independently of all the others. If it were nl instead of n it would have to be $(nl) or ${nl} to keep from being treated as ${n}l. The documentation seems to suggest a more robust way to achieve this, by the way:. I’m a big sucker for irrelevant nitpicks like properly quoting arguments in shell scripts. Then use -e with echo to interpret them. Smith. So, you can either use the \ at the end of lines for continuation as above or you can get everything on one line with the && operator in bash. It also removes the trailing (carriage-return and) newline, if it's the last thing in the result. So, the values are not carried over. 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. Also, a site note, the debug option is very useful when you are trying to figure out why a rule did not fire the way you had intended it. Viewed 3k times 6 . 3 - let us know if you come across something that breaks. Compiling I had read somewhere that you can define one. 6. GNU make The only processing make does on the result is to convert each newline (or carriage-return / newline pair) to a single space. ONESHELL as shown in this answer). Hence, for your given foo value, below recipe will raise a The program used as the shell is taken from the variable SHELL. g. 76 has been handled by Paul D. You may need to set the . When you run make with the ‘-i’ or ‘--ignore-errors’ flag, errors are ignored in all recipes of all rules. Great answer – Aaron D Running make with the following Makefile will instantly exit: a = $(shell sleep 3) Running make with the following Makefile will sleep for 3 seconds, and then exit: a := $(shell sleep 3) In the former Makefile, a is not evaluated until it's used elsewhere in the Makefile, while in the latter a is evaluated immediately even though it's not used. It might need a complete manual for checking how spaces and newlines are handled in each occasion. Joey Joey. Note that this code assumes that there is the requisite number of fields, otherwise the last field is repeated. Use the SHELL environment variable. SHELLFLAGS is -c normally, or -ec in POSIX-conforming mode. If you're targeting a usual or "patterned" file, just use make's internal variable $(@D), that means "the directory the current target Now, since I used quotes whenever I was manipulating the data, the newline characters (\n) always got interpreted by the shell, and therefore remained. GNU make has no limit on the length of a statement line, up to the amount of memory in your computer. 2,422 1 1 gold badge 25 25 silver badges 40 40 bronze badges. As in normal makefile syntax, a single logical recipe line can be split into multiple physical lines in the makefile by 5. The program used as the shell is taken from the variable SHELL. In fact, there really isn't any standard behavior which you can expect of echo. 1 Splitting Long Lines. You should create files and if a file creation needs a new directory then quietly create the directory within the rule for the relevant file. But I have tried what is mentioned here: define \n endef printit: @echo "${\n}Compiling" But this doesn't print the newline. One of the few ways in which make does interpret recipes is checking for a backslash just before the newline. I realise that they are stripped by default, so some manipulation may be required to keep them, and I want to keep the original exit code. 3. sh And call: make dump This also works like mentioned in the other answer: dump: $(shell . Basically, you want make to see something like:. Follow edited Mar 4, 2009 at 14:07. The make runs every command in its separate shell. Single-letter variable names don't suffer from this problem in Gnu make. Swiss Frank Swiss Frank. If The commands in a makefile recipe are executed by the shell, not by Make, and each line is executed in a new shell subprocess, so variables defined on previous lines are no longer defined after that line (unless you use . Placing the You can usually use the POSIX printf command (not the function) reliably: printf '\nCompiling\n' — and that doesn't depend on the vagaries of which shell is in use. The key message here, of course, is to choose a specific shell. You can't escape a newline, there's no syntax for special characters (e. That works fine, but make is not /bin/sh (or whatever shell your script is for) and does not understand that The short answer is, you should not ever use tcsh, at least not for makefiles. output a file with a variable name in shell There is a newline and tab before FILENAME and cp Multi line shell scripts may be used inside make by a backslash newline sequence in the make files. Or shell in combination with notdir, if you need not absolute path: current_dir = $(notdir $(shell pwd)). – Eric Miller \a alert (bell) \b backspace \e \E an escape character \f form feed \n new line \r carriage return \t horizontal tab \v vertical tab \\ backslash \' single quote \" double quote \nnn the eight-bit character whose value is the octal value nnn (one to three digits) \xHH the eight-bit character whose value is the hexadecimal value HH (one or two Note that changing the current working directory inside the makefile for the shell that invoked make is not possible, since that's a process' property, and the running make instance that will execute cd is another (sub)process. That is the same reason you cannot change the working directory of a shell by Assuming you have a string with spaces as separators: newline_separated=${space_separated// /$'\n'} However, you're probably asking the wrong question. I don't think that's a problem. sh 15 &' /bin/sh -c '. It'll be picked up by default (if you have more than one of these standard names in your build directory, you better look up the make Each individual logical line in a recipe is invoked in its own shell. sh I get to have a single Makefile and can just run make build, make deploy By default, each line of a recipe runs in a separate shell instance. It's how you reference the variable that makes the difference. Make manual 5. This approach also works without using . One possible workaround is to use a different mechanism for comments, such as the : shell no-op, which however is slightly . xterm -e vim "$@" Obviously fails. And echo will add a trailing newline by default so To force it to keep the newline, we can extend the snippet: blank := define newline $(blank) endef Finally, to actually get a separate shell command for each dependency, you need to run the How do I get the contents of the file into the make variable without losing the newlines? You can't. The make program uses the makefile description and the last-modification times of I want to be able to capture the exact output of a command substitution, including the trailing new line characters. You can wreak havoc on your shell instance by declaring variables, and especially modifying state with set, inside of {}. SHELL=bash to get an echo that does this. Makefiles have a similar facility, but unlike with C, a backslash-newline combination is not simply deleted; instead, the backslash-newline pair and any surrounding whitespace are together replaced with a single space character. login or some such) on the new system, which will cause problems for any program that tries Note the differences between Makefile variables and Shell variables in this next example. Follow answered Sep 7, 2020 at 3:45. If $(BAR) produces a dollar sign, that dollar sign is now just data inside FOO and won't be causing any more problems. sh) But the downside is that you don't get the shell commands from the console unless you store in a variable and echo it. So in a Makefile, the following three assignments to x An echo implementation which strictly conforms to the Single Unix Specification will add newlines if you do:. o: hello. This is a required You have several options to set up variables from outside your makefile: From environment - each environment variable is transformed into a makefile variable with the same name and value. When errors are to be ignored, because of either a ‘-’ or 5. You can also combine it with mktemp to store the output into a new tempfile each time, and clean that up as part of the build recipe that consumes whatever you will use this for. What could keep a giant The $@ and $< are called automatic variables. PHONY: job1 job1: ; . A function to do that: empty := tab := ${empty} # Trailing tab define \n := endef stanza = $(subst ${\n}, \${\n}${tab}) Long runs of shell syntax in a makefile are pretty smelly TBH. The same as writing any embeded shell script inside the makefile, you need to escape every new line. You don't tend to execute the make file itself, rather you execute make, giving it the make file as an argument:. () prevents the script from This works nicely because the C pre-processor simply deletes any backslash-newline pairs. Therefore, it will only change the working directory of that subprocess. /a. By default, the program `/bin/sh' is used. ONESHELL: or other similar non-portable workarounds). c. The only processing make does on the result, before substituting it into the surrounding text, is to convert each newline or carriage-return / newline pair to a single space. The basic issue is that a child process can not alter the parent's environment. The commands should really be joined by &&, because with ; if the directory doesn’t exist and the cd fails, the shell will keep running the rest of the commands in the current directory, which can cause things like mysterious “file not found” messages for compiles, infinite loops when invoking make, or disaster for rules like clean:: cd dir; rm -rf *. 0. make_var = I am a make variable I should have used it in every example with all or clean, but I wanted to keep the examples clean. PHONY: job3 job3: ; . echo 'line1\nline2' But that is not a reliable behavior. The default value of . Next, let’s take a look at the proper way to preserve linebreaks in the output. This directive has an unusual syntax which allows newline characters to be included in the value, which is convenient for defining both canned sequences of commands (see Defining Canned Recipes), and also sections of makefile syntax to use with eval (see The eval Function). , Also note the difference with HEADER = $(shell ) vs HEADER := $(shell ) where the former is expanded on every use and latter only once. The performance argument does not apply to modern make implementations since modern implementations try to avoid to call the shell in case that the command line does not contain shell specific meta characters. If there is a trailing (carriage-return and) newline it will simply be removed. However, an explicit assignment in the makefile, or with a command argument, overrides the environment. exe makefile. PHONY: job2 job2: ; . IGNORE has the same effect, if there are no prerequisites. . 1 with SHELL=/bin/bash atop my Makefile, so YMMV! This allows us to accept extra arguments (by doing nothing when we get a job that doesn't match, rather than throwing an error). ? – Kent Pawar. out 2 . Makefile: Line break / continuation character usage: `\`, generally acceptable or The program used as the shell is taken from the variable SHELL. I have a makefile rule in while I am executing a linux tool. There is an appendix at the end of the chapter that describes the differences between Z-Shell and Bash-like shells (which tend to be closer to the Posix standard). Perhaps like this: myitem: d=$$(date +%s)\ ; build \ && echo "Build took $$(($$(date +%s)-d)) seconds" The backslashes escape the newlines so that this is seen as a single long logical line by make. I'm using GNU Make 4. bashrc) can be specified for Bash to source. The commands run by calls to the shell function are run when the function calls are expanded (see How make Reads a Makefile). Each update command in a Makefile rule is executed in a separate shell. By default make uses /bin/sh as the shell which executes recipe lines. My personal opinion is that it's high time csh and all derivatives were relegated to the dustbin of history, for all purposes. Then you can use a test command to test if the file does exist, e. Where the shell doesn't expect or won't correctly interpret a quoted string, you should not use quotes. mk If your make file is actually one of the standard names (like makefile or Makefile), you don't even need to specify it. So your makefile is basically running this: test: /bin/sh -c 'echo "START"' /bin/sh -c '. 5. output=$(head $file) keeps embedded newlines in the value of output, and trims all trailing newlines. Unlike most variables, the variable SHELL is never set from the environment. Setting SHELL := /bin/bash or anything similar won't have any effect (which you can debug by running make -d), The thing is you need to escape the newline characters in your foo variable or pass its value to a proper place. in a script-file. STRING := foo bar baz SPLIT := $(shell echo "${STRING}" | sed -e 's/ /\n/g') Or, slightly better, if your shell is Then cd to your directory, where you have the makefile and Try using mingw32-make. Unlike most variables, the Every quoting character you write in a makefile will be kept as a literal quote and passed along as-is to the commands that make invokes. Run an interactive bash subshell with initial commands without returning to the super shell immediately looked promising. But they definitely are not usable in makefiles. The for loop has split up the sentence variable into a set of words. o is the output file. Share. SHELLFLAGS. sh 10 &' /bin/sh -c 'wait' /bin/sh -c 'echo "DONE"' You should make it all run in a single shell using semicolons and When a makefile refers to files whose build commands are in different makefiles, makepp automatically finds the appropriate build rules in the other makefiles. For example, given a command with a variable number of trailing newlines and exit code: There is no direct support for this; # in a Makefile comments out any final backslash, too, breaking the requirement to keep shell commands on a single logical line (absent . It doesn't It can be difficult to split lines in GNU Makefiles for better readability without changing their meaning; but there are several ways to work around the line-continuation rules. lyyxmhaadcbzlipndsfblcjufbtrzfaotwjukrzkygmxbbhpptfuusowzctmooctksxxoyn
