Is it possible to have different working directories for various commands in the same custom target in CMake?

I'm trying to understand, is it possible to specify multiple working directories for different commands?

I added a custom target called run_projects:

add_custom_target(run_projects
    COMMAND first_project &
    COMMAND second_project
    COMMAND killall first_project &> /dev/null &
    COMMAND killall second_project &> /dev/null
    WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
)

It should run executable projects: first_project + second_project.
The problem is resources of first_project in root directory:
${PROJECT_SOURCE_DIR}, but second_project resources is in ${PROJECT_SOURCE_DIR}/second_project

my_project:
    resources/ <- resources of first_project outside apps/first_project dir
    second_project/resources/ <- resources of second project inside second_project dir

Any chance to make it work via CMake only?

As far as documentation goes, no. The command signature as documented is:

add_custom_target(Name [ALL] [command1 [args1...]]
                  [COMMAND command2 [args2...] ...]
                  [DEPENDS depend depend depend ... ]
                  [BYPRODUCTS [files...]]
                  [WORKING_DIRECTORY dir]
                  [COMMENT comment]
                  [JOB_POOL job_pool]
                  [VERBATIM] [USES_TERMINAL]
                  [COMMAND_EXPAND_LISTS]
                  [SOURCES src1 [src2...]])

I would split what you're doing into separate custom targets (or custom commands if you don't want the commands to always run), and specify the dependencies between them using the DEPENDS fields or add_dependencies. That way, you can specify the working directory for each one specifically.

It looks as though you're trying to use shell-specific things like Bash's run-in-background operator (&). If you write your commands each in their own custom command / target, as long as the buildsystem generator you have chosen supports building/running targets in parallel, then you will get what you want by default, and it will be cross-platform automatically (instead of depending on the syntax of a specific shell).

I did do a quick test on my Ubuntu machine with Ninja and the following:

add_custom_target(
cd ALL
COMMAND pwd
COMMAND cd build
COMMAND pwd
COMMAND cd ..
COMMAND pwd
WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
)

, which CMake generates to run as cd /home/david/code/mine/cmake-playground/16 && pwd && cd build && pwd && cd .. && pwd && echo hi, which shows that it's possible to cd around places in between each command on at least one platform + generator combination.

But you shouldn't rely on this behaviour. It's an internal / implementation detail. The documentation for add_custom_target's COMMAND argument says:

> Specify the command-line(s) to execute at build time. If more than one COMMAND is specified they will be executed in order, but not necessarily composed into a stateful shell or batch script. (To run a full script, use the configure_file() command or the file(GENERATE) command to create it, and then specify a COMMAND to launch it.)