CMake Variables

Variables that Provide Information

• CMAKE_CURRENT_SOURCE_DIR The path to the source directory currently being processed.

• CMAKE_CURRENT_BINARY_DIR The path to the binary directory currently being processed.

• CMAKE_SOURCE_DIR The path to the top level of the source tree.

• CMAKE_BINARY_DIR The path to the binary directory currently being processed.

  • for an in-source build, this would be the same as CMAKE_SOURCE_DIR

  • for an out-of-source build, this would be at ./build folder

• PROJECT_SOURCE_DIR Top level source directory for the current project.

• PROJECT_BINARY_DIR Full path to build directory for project.

• <PROJECT-NAME>_SOURCE_DIR Top level source directory for the named project.

• <PROJECT-NAME>_BINARY_DIR Top level binary directory for the named project.

• PROJECT_VERSION Value given to the VERSION option of the most recent call to the project() command, if any.

• CMAKE_VERSION

• CMAKE_COMMAND The full path to the cmake executable.

• CMAKE_GENERATOR The generator used to build the project.

# ~/catkin_ws/src/example_pkg
message(${CMAKE_CURRENT_SOURCE_DIR})
message(${CMAKE_SOURCE_DIR})
message(${PROJECT_SOURCE_DIR})

# ~/catkin_ws/build/example_pkg
message(${CMAKE_CURRENT_BINARY_DIR})
message(${CMAKE_BINARY_DIR})
message(${PROJECT_BINARY_DIR})

Variables that Change Behavior

• CMAKE_BUILD_TYPE Specifies the build type on single-configuration generators.

  • Can be set to Debug, Release, RelWithDebInfo, MinSizeRel, ...

• CMAKE_CONFIGURATION_TYPES Specifies the available build types on multi-config generators.

• CMAKE_MODULE_PATH List of directories to search for CMake modules.

  • Commands like include() and find_package() search for files in directories listed by this variable before checking the default modules that come with CMake.

• CMAKE_INSTALL_PREFIX Install directory used by install.

  • If “make install” is invoked or INSTALL is built, this directory is prepended onto all install directories.

  • This variable defaults to /usr/local on UNIX and c:/Program Files on Windows.

CMAKE_XXX_PATH

By default it is empty, it is intended to be set by the project.

• CMAKE_PREFIX_PATH Path used for searching by FIND_XXX(), with appropriate suffixes added.

  • a.k.a. CATKIN_DEVEL_PREFIX in earlier CMake versions; set to catkin_ws/devel for example.

  • It contains the “base” directories, the FIND_XXX() commands append appropriate subdirectories to the base directories.

    • FIND_PROGRAM() adds /bin to each of the directories in the path,

    • FIND_LIBRARY() appends /lib to each of the directories, and

    • FIND_FILE() and FIND_PATH() append /include.

• CMAKE_IGNORE_PATH Path to be ignored by FIND_XXX() commands.

  • This is useful in cross-compiled environments where some system directories contain incompatible but possibly linkable libraries.

• CMAKE_INCLUDE_PATH Path used for searching by FIND_FILE() and FIND_PATH().

• CMAKE_LIBRARY_PATH Path used for searching by FIND_LIBRARY().

• CMAKE_PROGRAM_PATH Path used for searching by FIND_PROGRAM().

CMAKE_SYSTEM_XXX_PATH

By default it contains the standard directories for the current system. It is NOT intended to be modified by the project.

• CMAKE_SYSTEM_IGNORE_PATH

• CMAKE_SYSTEM_INCLUDE_PATH

• CMAKE_SYSTEM_LIBRARY_PATH

• CMAKE_SYSTEM_PREFIX_PATH

• CMAKE_SYSTEM_PROGRAM_PATH

message("${CMAKE_BUILD_TYPE}")  # add "" to prevent error from empty variable
message("${CMAKE_CONFIGURATION_TYPES}")
message("${CMAKE_MODULE_PATH}")
message("${CMAKE_INSTALL_PREFIX}")

Variables that Describe the System

• CMAKE_HOST_SYSTEM

• CMAKE_SYSTEM_NAME

• UNIX or CMAKE_HOST_UNIX

• WIN32 or CMAKE_HOST_WIN32

• MSVC, MSVC_VERSION

• ENV: Access environment variables.

  • Use the syntax $ENV{VAR} to read environment variable VAR.

  • See also the set() command to set ENV{VAR}.

Variables that Control the Build

• EXECUTABLE_OUTPUT_PATH

• LIBRARY_OUTPUT_PATH

• CMAKE_RUNTIME_OUTPUT_DIRECTORY Where to put all the RUNTIME targets when built.

  • This variable is used to initialize the RUNTIME_OUTPUT_DIRECTORY property on all the targets.

  • See that target property for additional information.

Variables for Languages

• CMAKE_<LANG>_COMPILER The full path to the compiler for LANG.

  • CMAKE_CXX_COMPILER, CMAKE_C_COMPILER

• CMAKE_<LANG>_FLAGS Flags for all build types.

  • CMAKE_CXX_FLAGS, CMAKE_C_FLAGS

  • CMAKE_<LANG>_FLAGS_RELEASE Flags for Release build type or configuration.

• CMAKE_CXX_STANDARD New in version 3.1. Default value for CXX_STANDARD property of targets.

• CMAKE_CUDA_STANDARDNew in version 3.8. Default value for CUDA_STANDARD property of targets.