how to prevent directory already exists error in a makefile when using mkdir

Question

I need to generate a directory in my makefile and I would like to not get the  directory already exists error  over and over even though I can easily ignore it   I mainly use mingw msys but would like something that works across other shells systems  too   I tried this but it didn t work  any ideas   ifeq     findstring   OBJDIR    wildcard   OBJDIR      -mkdir   OBJDIR  endif

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Inside your makefile   target      if test -d dir  then echo  hello world    else mkdir dir  fi

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On Windows    if not exist    OBJDIR   mkdir   OBJDIR    On Unix   Linux   if     -d    OBJDIR      then mkdir   OBJDIR   fi

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You can use the test command   test -d   OBJDIR     mkdir   OBJDIR

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ifeq    wildcard   MY DIRNAME          -mkdir   MY DIRNAME  endif

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ifeq    wildcard   MY DIRNAME          -mkdir   MY DIRNAME  endif

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If having the directory already exist is not a problem for you  you could just redirect stderr for that command  getting rid of the error message   -mkdir   OBJDIR  2 gt  dev null

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OBJDIR       mkdir      Which also works for multiple directories  e g    OBJDIRS      sort   dir   OBJECTS       OBJDIRS       mkdir      Adding   OBJDIR  as the first target works well

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If you explicitly ignore the return code and dump the error stream then your make will ignore the error if it occurs   mkdir 2 gt  dev null    true   This should not cause a race hazard in a parallel make - but I haven t tested it to be sure

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Looking at the official make documentation  here is a good way to do it   OBJDIR    objdir OBJS      addprefix   OBJDIR   foo o bar o baz o     OBJDIR    o     c       COMPILE c    OUTPUT OPTION    lt   all    OBJS     OBJS       OBJDIR     OBJDIR       mkdir -p   OBJDIR    You should see here the usage of the   pipe operator  defining an order only prerequisite  Meaning that the   OBJDIR  target should be existent  instead of more recent  in order to build the current target   Note that I used mkdir -p  The -p flag was added compared to the example of the docs  See other answers for another alternative

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OBJDIR       mkdir      Which also works for multiple directories  e g    OBJDIRS      sort   dir   OBJECTS       OBJDIRS       mkdir      Adding   OBJDIR  as the first target works well

User · Answer

On UNIX Just use this   mkdir -p   OBJDIR    The -p option to mkdir prevents the error message if the directory exists

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Here is a trick I use with GNU make for creating compiler-output directories  First define this rule        d            mkdir -p    D            touch      Then make all files that go into the directory dependent on the  d file in that directory    obj   o    c obj  d       CC    CFLAGS  -c -o      lt    Note use of   lt  instead of       Finally prevent the  d files from being removed automatically     PRECIOUS     d   Skipping the  d file  and depending directly on the directory  will not work  as the directory modification time is updated every time a file is written in that directory  which would force rebuild at every invocation of make

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If having the directory already exist is not a problem for you  you could just redirect stderr for that command  getting rid of the error message   -mkdir   OBJDIR  2 gt  dev null

User · Answer

You can use the test command   test -d   OBJDIR     mkdir   OBJDIR

User · Answer

A little simpler than Lars  answer   something needs directory xxx   xxx      and generic rule            mkdir -p    D    No touch-files to clean up or make  PRECIOUS  -   If you want to see another little generic gmake trick  or if you re interested in non-recursive make with minimal scaffolding  you might care to check out Two more cheap gmake tricks and the other make-related posts in that blog

User · Answer

Here is a trick I use with GNU make for creating compiler-output directories  First define this rule        d            mkdir -p    D            touch      Then make all files that go into the directory dependent on the  d file in that directory    obj   o    c obj  d       CC    CFLAGS  -c -o      lt    Note use of   lt  instead of       Finally prevent the  d files from being removed automatically     PRECIOUS     d   Skipping the  d file  and depending directly on the directory  will not work  as the directory modification time is updated every time a file is written in that directory  which would force rebuild at every invocation of make

User · Answer

Inside your makefile   target      if test -d dir  then echo  hello world    else mkdir dir  fi

User · Answer

Inside your makefile   target      if test -d dir  then echo  hello world    else mkdir dir  fi

User · Answer

You can use the test command   test -d   OBJDIR     mkdir   OBJDIR

User · Answer

On UNIX Just use this   mkdir -p   OBJDIR    The -p option to mkdir prevents the error message if the directory exists

User · Answer

If having the directory already exist is not a problem for you  you could just redirect stderr for that command  getting rid of the error message   -mkdir   OBJDIR  2 gt  dev null

User · Answer

If you explicitly ignore the return code and dump the error stream then your make will ignore the error if it occurs   mkdir 2 gt  dev null    true   This should not cause a race hazard in a parallel make - but I haven t tested it to be sure

User · Answer

Inside your makefile   target      if test -d dir  then echo  hello world    else mkdir dir  fi

User · Answer

You can use the test command   test -d   OBJDIR     mkdir   OBJDIR

User · Answer

On UNIX Just use this   mkdir -p   OBJDIR    The -p option to mkdir prevents the error message if the directory exists

User · Answer

It works under mingw32 msys cygwin linux  ifeq    wildcard  dep      -include   shell mkdir  dep    wildcard  dep    endif

User · Answer

ifeq    wildcard   MY DIRNAME          -mkdir   MY DIRNAME  endif

User · Answer

Looking at the official make documentation  here is a good way to do it   OBJDIR    objdir OBJS      addprefix   OBJDIR   foo o bar o baz o     OBJDIR    o     c       COMPILE c    OUTPUT OPTION    lt   all    OBJS     OBJS       OBJDIR     OBJDIR       mkdir -p   OBJDIR    You should see here the usage of the   pipe operator  defining an order only prerequisite  Meaning that the   OBJDIR  target should be existent  instead of more recent  in order to build the current target   Note that I used mkdir -p  The -p flag was added compared to the example of the docs  See other answers for another alternative

User · Answer

OBJDIR       mkdir      Which also works for multiple directories  e g    OBJDIRS      sort   dir   OBJECTS       OBJDIRS       mkdir      Adding   OBJDIR  as the first target works well

User · Answer

If having the directory already exist is not a problem for you  you could just redirect stderr for that command  getting rid of the error message   -mkdir   OBJDIR  2 gt  dev null

User · Answer

On Windows    if not exist    OBJDIR   mkdir   OBJDIR    On Unix   Linux   if     -d    OBJDIR      then mkdir   OBJDIR   fi

User · Answer

A little simpler than Lars  answer   something needs directory xxx   xxx      and generic rule            mkdir -p    D    No touch-files to clean up or make  PRECIOUS  -   If you want to see another little generic gmake trick  or if you re interested in non-recursive make with minimal scaffolding  you might care to check out Two more cheap gmake tricks and the other make-related posts in that blog

User · Answer

It works under mingw32 msys cygwin linux  ifeq    wildcard  dep      -include   shell mkdir  dep    wildcard  dep    endif

User · Answer

OBJDIR       mkdir      Which also works for multiple directories  e g    OBJDIRS      sort   dir   OBJECTS       OBJDIRS       mkdir      Adding   OBJDIR  as the first target works well

User · Answer

On UNIX Just use this   mkdir -p   OBJDIR    The -p option to mkdir prevents the error message if the directory exists

User · Answer

ifeq    wildcard   MY DIRNAME          -mkdir   MY DIRNAME  endif

[makefile] how to prevent "directory already exists error" in a makefile when using mkdir

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