How do I write the cd command in a makefile

Question

For example  I have something like this in my makefile   all       cd some directory   But when I typed make I saw only  cd some directory   like in the echo command

User · Answer

Starting from GNU make 3 82  July 2010   you can use the  ONESHELL special target to run all recipe lines in a single instantiation of the shell  bold emphasis mine     New special target   ONESHELL instructs make to invoke a single instance of the shell and provide it with the entire recipe  regardless of how many lines it contains     ONESHELL    Only applies to all target all      cd   some dir     pwd   Prints   some dir if cd succeeded  another rule      cd   some dir     pwd   Oops  prints

User · Answer

Like this   target        shell cd                    commands execution in this directory           no need to go back  using  cd -  or so            next target will be automatically in prev dir   Good luck

User · Answer

Here s a cute trick to deal with directories and make   Instead of using multiline strings  or  cd    on each command  define a simple chdir function as so   CHDIR SHELL      SHELL  define chdir      eval  D   firstword   1     D         info   MAKE   cd    D     eval SHELL   cd    D     CHDIR SHELL   endef   Then all you have to do is call it in your rule as so   all              call chdir some dir            echo  I m now always in some dir            gcc -Wall -o myTest myTest c   You can even do the following   some dir myTest              call chdir            echo  I m now always in some dir            gcc -Wall -o myTest myTest c

User · Answer

Here is the pattern I ve used   PHONY  test py utils PY UTILS DIR   py utils test py utils      cd   PY UTILS DIR   amp  amp  black       cd   PY UTILS DIR   amp  amp  isort       cd   PY UTILS DIR   amp  amp  mypy       cd   PY UTILS DIR   amp  amp  pytest -sl       cd   PY UTILS DIR   amp  amp  flake8     My motivations for this pattern are   The above solution is simple and readable I read the classic paper  quot Recursive Make Considered Harmful quot   which discouraged me from using   MAKE  -C some dir all I didn t want to use just one line of code  punctuated by semicolons or  amp  amp   because it is less readable  and I fear that I will make a typo when editing the make recipe  I didn t want to use the  ONESHELL special target because   that is a global option that affects all recipes in the makefile using  ONESHELL causes all lines of the recipe to be executed even if one of the earlier lines has failed with a nonzero exit status  Workarounds like calling set -e are possible  but such workarounds would have to be implemented for every recipe in the makefile

User · Answer

It is actually executing the command  changing the directory to some directory  however  this is performed in a sub-process shell  and affects neither make nor the shell you re working from   If you re looking to perform more tasks within some directory  you need to add a semi-colon and append the other commands as well  Note that you cannot use newlines as they are interpreted by make as the end of the rule  so any newlines you use for clarity needs to be escaped by a backslash   For example   all          cd some dir  echo  I m in some dir               gcc -Wall -o myTest myTest c   Note also that the semicolon is necessary between every command even though you add a backslash and a newline  This is due to the fact that the entire string is parsed as a single line by the shell  As noted in the comments  you should use   amp  amp   to join commands  which mean they only get executed if the preceding command was successful   all          cd some dir  amp  amp  echo  I m in some dir   amp  amp              gcc -Wall -o myTest myTest c   This is especially crucial when doing destructive work  such as clean-up  as you ll otherwise destroy the wrong stuff  should the cd fail for whatever reason   A common usage though is to call make in the sub directory  which you might want to look into  There s a command line option for this so you don t have to call cd yourself  so your rule would look like this  all            MAKE  -C some dir all   which will change into some dir and execute the Makefile in there with the target  all   As a best practice  use   MAKE  instead of calling make directly  as it ll take care to call the right make instance  if you  for example  use a special make version for your build environment   as well as provide slightly different behavior when running using certain switches  such as -t   For the record  make always echos the command it executes  unless explicitly suppressed   even if it has no output  which is what you re seeing

User · Answer

What do you want it to do once it gets there  Each command is executed in a subshell  so the subshell changes directory  but the end result is that the next command is still in the current directory   With GNU make  you can do something like   BIN  bin foo        shell cd   BIN   ls

User · Answer

To change dir   foo         MAKE  -C mydir  multi        MAKE  -C   -C my-custom-dir      Equivalent to  my-custom-dir

[makefile] How do I write the 'cd' command in a makefile?

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