Setting environment variables to ExternalProject_Add context

Question

I have a CMakeLists.txt file in which there are multiple external projects I need to build. I am using the ExternalProject_Add feature of CMake.

I need to set an environment variable in one of the ExternalProject_Add project modules. The project needs it to perform a build.

I have tried using the ${CMAKE_COMMAND} -E env option and that has not worked:

CONFIGURE_COMMAND
    ${CMAKE_COMMAND} -E env ANDROID_SDK_ROOT="/home/subbu/Android/Sdk"
    ${CMAKE_COMMAND} -E env ANDROID_API_VERSION="android-22"
    <SOURCE_DIR>/configure
    -prefix <INSTALL_DIR>
    -debug

I am not able to find examples on the web.

Please advise.

Thanks for your help in advance.

Subbu

Description "that has not worked" is not useful. What exactly is wrong with that approach? Do you have an error or something else? Please, be specific when describe the problem. You approach should set variable for configuration stage (but not for other stages: build, test, etc.). But it is better to remove the second ${CMAKE_COMMAND} -E env: you may specify several environment variables inside a single cmake -E env wrapper. — Tsyvarev
BTW, here an example: stackoverflow.com/questions/55708589/…. — Tsyvarev
@Tsyvarev - I am building the Qt library using the ExternalProject_Add feature. I am calling the "configure" script through the cmake configure command to prepare Qt for a build later. However this configure requires that I set the ANDROID_SDK_ROOT and ANDROID_API_VERSION environment variables for it to be successful. I will try your example. Thanks for your reply!!! — Subbu

j-mo j-mo · Accepted Answer · 2021-08-07T01:01:35

i was doing a similar thing for msgpack, and i was able to get it to work by doing the following:

set (MsgpackBundle msgpack-1.4.1.tar.gz)
ExternalProject_Add(MsgpackBuilder
    URL ${CMAKE_CURRENT_SOURCE_DIR}/${MsgpackBundle}
    URL_MD5 ${MsgpackBundleMd5}
    CONFIGURE_COMMAND
    ${CMAKE_COMMAND} -E CFLAGS=${MsgpackCflags}
    ${CMAKE_COMMAND} -E env CXXFLAGS=${MsgpackCflags}
    ${CMAKE_COMMAND} -E env LDFLAGS=${MsgpackLdflags}
    ./configure
         --prefix=${DependenciesInstallDir}
         --host=${MsgpackHost}
         --disable-shared
    BUILD_IN_SOURCE true
    BUILD_COMMAND
    make V=1
    INSTALL_COMMAND
    make install)

MsgpackCflags, MsgpackLdflags are pre-computed, depending on the target system. MsgpackHost is used by the cross-compile toolchain (x86_64-linux-gnu for a host build), ${DependenciesInstallDir} is also a pre-computed path that varies for different os/architecture/build-configuration (debug, release) tuple. the MsgpackbundleMd5 is the result of md5sum msgpack-1.4.1.tar.gz.

Setting environment variables to ExternalProject_Add context

1 Answers