Create directories using make file

Question

I m a very new to makefiles and i want to create directories using makefile  My project directory is like this   --Project       --output       --source         Testfile cpp       Makefile     I want to put all the objects and output into the respective output folder  I want to create folder structure which would be like this after compiling    --Project     --output       --debug  or release          --objs           Testfile o         Testfile  my executable file      --source       Testfile cpp     Makefile   I tried with several options  but could not succeed  Please help me to make directories using make file  I m posting my Makefile for your consideration    ---------------------------------------------------------------------   Input dirs  names  files  --------------------------------------------------------------------- OUTPUT ROOT    output   TITLE NAME    TestProj   ifdef DEBUG      TITLE NAME     DEBUG else ifdef RELEASE     TITLE NAME     RELEASE endif endif     Include all the source files here with the directory tree SOURCES              source TestFile cpp     ---------------------------------------------------------------------   configs  --------------------------------------------------------------------- ifdef DEBUG OUT DIR          OUTPUT ROOT debug CC FLAGS       -c -Wall else ifdef RELEASE OUT DIR          OUTPUT ROOT release CC FLAGS       -c -Wall else   error no build type defined  endif endif    Put objects in the output directory  OUT O DIR        OUT DIR  objs   ---------------------------------------------------------------------   settings  --------------------------------------------------------------------- OBJS     SOURCES  cpp  o  DIRS     subst       sort   dir   OBJS     DIR TARGET     OUT DIR   OUTPUT TARGET     OUT DIR    TITLE NAME   CC FLAGS        LCF FLAGS      LD FLAGS       ---------------------------------------------------------------------   executables  --------------------------------------------------------------------- MD    mkdir RM    rm CC    g     ---------------------------------------------------------------------   rules  ---------------------------------------------------------------------  PHONY  all clean title   all  title   clean        RM  -rf   OUT DIR     DIR TARGET         MD  -p   DIRS    cpp o          CC  -c   lt  -o       OBJS     OUT O DIR    o    cpp        CC  -c   lt  -o     title    DIR TARGET    OBJS    Thanks in advance  Please guide me if i made any mistakes also

User · Answer

I ve just come up with a fairly reasonable solution that lets you define the files to build and have directories be automatically created  First  define a variable ALL TARGET FILES that holds the file name of every file that your makefile will be build  Then use the following code   define depend on dir   1       dir   1    ifndef   dir   1   DIRECTORY RULE IS DEFINED   dir   1        mkdir -p        dir   1   DIRECTORY RULE IS DEFINED    1 endif endef    foreach file   ALL TARGET FILES    eval   call depend on dir   file       Here s how it works  I define a function depend on dir which takes a file name and generates a rule that makes the file depend on the directory that contains it and then defines a rule to create that directory if necessary  Then I use foreach to call this function on each file name and eval the result   Note that you ll need a version of GNU make that supports eval  which I think is versions 3 81 and higher

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OS independence is critical for me  so mkdir -p is not an option  I created this series of functions that use eval to create directory targets with the prerequisite on the parent directory  This has the benefit that make -j 2 will work without issue since the dependencies are correctly determined       convenience function for getting parent directory  will eventually return            call get parent dir somewhere on earth   - gt  somewhere on  get parent dir   dir   patsubst       1      function to create directory targets    All directories have order-only-prerequisites on their parent directories   https   www gnu org software make manual html node Prerequisite-Types html Prerequisite-Types TARGET DIRS   define make dirs recursively TARGET DIRS   1  1      if   subst       call get parent dir  1     call get parent dir  1       mkdir  1 endef    function to recursively get all directories          call get all dirs things and places   - gt  things  things and  things and places          call get all dirs things and places  - gt  things  things and  get all dirs   if   subst       dir  1     call get all dirs   call get parent dir  1    1     function to turn all targets into directories         call get all target dirs obj a o obj three b o  - gt  obj  obj three  get all target dirs   sort   foreach target  1   call get all dirs   dir   target         create target dirs create dirs   foreach dirname   call get all target dirs  1    eval   call make dirs recursively   dirname      TARGETS    w h a t e v e r things dat w h a t things dat  all    TARGETS     this must be placed after your  DEFAULT GOAL  or you can manually state what it is   https   www gnu org software make manual html node Special-Variables html   call create dirs   TARGETS        TARGET DIRS  needs to be an order-only-prerequisite w h a t e v e r things dat  w h a t things dat     TARGET DIRS      echo whatever happens  gt      w h a t things dat      TARGET DIRS      echo whatever happens  gt       For example  running the above will create     make mkdir w  mkdir w h  mkdir w h a  mkdir w h a t  mkdir w h a t e  mkdir w h a t e v  mkdir w h a t e v e  mkdir w h a t e v e r  echo whatever happens  gt  w h a t things dat echo whatever happens  gt  w h a t e v e r things dat

User · Answer

make in  and off itself  handles directory targets just the same as file targets  So  it s easy to write rules like this   outDir someTarget  Makefile outDir     touch outDir someTarget  outDir      mkdir -p outDir   The only problem with that is  that the directories timestamp depends on what is done to the files inside  For the rules above  this leads to the following result     make mkdir -p outDir touch outDir someTarget   make touch outDir someTarget   make touch outDir someTarget   make touch outDir someTarget   This is most definitely not what you want  Whenever you touch the file  you also touch the directory  And since the file depends on the directory  the file consequently appears to be out of date  forcing it to be rebuilt   However  you can easily break this loop by telling make to ignore the timestamp of the directory  This is done by declaring the directory as an order-only prerequsite     The pipe symbol tells make that the following prerequisites are order-only                                                           v outDir someTarget  Makefile   outDir     touch outDir someTarget  outDir      mkdir -p outDir   This correctly yields     make mkdir -p outDir touch outDir someTarget   make make   outDir someTarget  is up to date      TL DR   Write a rule to create the directory     OUT DIR       mkdir -p   OUT DIR    And have the targets for the stuff inside depend on the directory order-only     OUT DIR  someTarget          OUT DIR

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This would do it - assuming a Unix-like environment   MKDIR P   mkdir -p   PHONY  directories  all  directories program  directories    OUT DIR     OUT DIR             MKDIR P    OUT DIR    This would have to be run in the top-level directory - or the definition of   OUT DIR  would have to be correct relative to where it is run   Of course  if you follow the edicts of Peter Miller s  Recursive Make Considered Harmful  paper  then you ll be running make in the top-level directory anyway   I m playing with this  RMCH  at the moment   It needed a bit of adaptation to the suite of software that I am using as a test ground   The suite has a dozen separate programs built with source spread across 15 directories  some of it shared   But with a bit of care  it can be done   OTOH  it might not be appropriate for a newbie     As noted in the comments  listing the  mkdir  command as the action for  directories  is wrong   As also noted in the comments  there are other ways to fix the  do not know how to make output debug  error that results   One is to remove the dependency on the the  directories  line   This works because  mkdir -p  does not generate errors if all the directories it is asked to create already exist   The other is the mechanism shown  which will only attempt to create the directory if it does not exist   The  as amended  version is what I had in mind last night - but both techniques work  and both have problems if output debug exists but is a file rather than a directory

User · Answer

Or  KISS   DIRS build build bins          shell mkdir -p   DIRS     This will create all the directories after the Makefile is parsed

User · Answer

In my opinion  directories should not be considered targets of your makefile  either in technical or in design sense   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   If you re targeting a usual or  patterned  file  just use make s internal variable    D   that means  the directory the current target resides in   cmp  with    for the target    For example     OUT O DIR    o    cpp          mkdir -p    D             CC  -c   lt  -o     title    OBJS    Then  you re effectively doing the same  create directories for all   OBJS   but you ll do it in a less complicated way   The same policy  files are targets  directories never are  is used in various applications   For example  git revision control system doesn t store directories     Note  If you re going to use it  it might be useful to introduce a convenience variable and utilize make s expansion rules   dir guard  mkdir -p    D     OUT O DIR    o    cpp           dir guard             CC  -c   lt  -o       OUT O DIR DEBUG    o    cpp           dir guard             CC  -g -c   lt  -o     title    OBJS

User · Answer

given that you re a newbie  I d say don t try to do this yet   it s definitely possible  but will needlessly complicate your Makefile   stick to the simple ways until you re more comfortable with make   that said  one way to build in a directory different from the source directory is VPATH  i prefer pattern rules

User · Answer

See https   www oreilly com library view managing-projects-with 0596006101 ch12 html  REQUIRED DIRS        MKDIRS      shell for d in   REQUIRED DIRS                  do                                                   -d   d       mkdir -p   d                  done     objects      sources    As I use Ubuntu  I also needed add this at the top of my Makefile   SHELL     bin bash   Use bash syntax

User · Answer

All solutions including the accepted one have some issues as stated in their respective comments  The accepted answer by  jonathan-leffler is already quite good but does not take into effect that prerequisites are not necessarily to be built in order  during make -j for example   However simply moving the directories prerequisite from all to program provokes rebuilds on every run AFAICT  The following solution does not have that problem and AFAICS works as intended   MKDIR P    mkdir -p OUT DIR    build   PHONY  directories all clean  all    OUT DIR  program  directories    OUT DIR     OUT DIR         MKDIR P    OUT DIR     OUT DIR  program    directories     touch   OUT DIR  program  clean      rm -rf   OUT DIR

[makefile] Create directories using make file

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