I have a build which is currently set up with steps as follows:
cmake
make
cpack -G TGZ
cpack -G RPM
I now have a problem in that there are files I wish to include in the RPM but not the tarball. Is there a way to make the install command conditional according to the generator used?
The simple and obvious way is wrong:
if (NOT ${PACKAGE_TYPE} STREQUAL "TGZ")
message("HELLO ${PACKAGE_TYPE}")
install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/foobar DESTINATION "/usr/lib" COMPONENT core RENAME "/usr/lib/only-install-me-for-RPM")
endif()
I believe it is wrong because the configure stage (running cmake) evaluates the conditional but cpack does not.
I do not want two builds as the install stage is the only part different. I do want more than one kind of installation package.
Background
Why do I want to do such an odd thing? I can think of other legitimate reasons but in this case it is because of the introduction of /usr/lib/.build-id.
It is not possible to disable this behaviour from cmake (though it is possible in the .spec file see https://bugzilla.redhat.com/show_bug.cgi?id=1724153)
In RHEL8 rpmbuild installs files (actually links) in /usr/lib/.build-id which I have not specificed myself.
In order to persuade cmake to make /usr/lib relocatable I have to install a dummy file in /usr/lib - see https://gitlab.kitware.com/cmake/cmake/-/issues/20691
This is not necessary for the tarball.
Currently used CPack generator can be retrieved from CPACK_GENERATOR variable. But this meaning works only inside a script specified with CPACK_PROJECT_CONFIG_FILE variable. Inside CMakeLists.txt the variable CPACK_GENERATOR has other meaning.
Because install command can only be issued in CMakeLists.txt, this command cannot be made conditional (based on CPack generator). But you may assign a COMPONENT for this installation. This component can be excluded from the components list later.
CMakeLists.txt:
# Assign 'core_special' COMPONENT for installation
install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/foobar DESTINATION "/usr/lib" COMPONENT core_special RENAME "/usr/lib/only-install-me-for-RPM")
# ...
# Set config script for CPack.
set(CPACK_PROJECT_CONFIG_FILE "${CMAKE_SOURCE_DIR}/cpack_project_config.cmake")
cpack_project_config.cmake:
# Exclude component "core_special" for all CPack generators except TGZ.
if (NOT CPACK_GENERATOR STREQUAL "TGZ")
list(REMOVE_ITEM CPACK_COMPONENTS_ALL "core_special")
endif()
# Need to set 'CMAKE_<GENERATOR>_COMPONENT_INSTALL' to ON, otherwise CPack ignores CPACK_COMPONENTS_ALL variable
set(CPACK_ARCHIVE_COMPONENT_INSTALL ON)
set(CPACK_RPM_COMPONENT_INSTALL ON)
# E.g create single archive/package from all components
# (other values - "IGNORE", "ONE_PER_GROUP" - will also work)
set(CPACK_COMPONENTS_GROUPING "ALL_COMPONENTS_IN_ONE")
How do I set CMAKE_INSTALL_PREFIX in my root CMakeLists.txt file?
I have been doing
cmake_minimum_required(VERSION 2.8)
project(MyProject)
# Set default install prefix
set(CMAKE_INSTALL_PREFIX ${CMAKE_SOURCE_DIR})
with the hopes that by installations would be destined to folders in the source tree. That is,
install(TARGETS my_exe DESTINATION bin/)
would install to ${CMAKE_SOURCE_DIR}/bin/. Instead, it keeps trying to write to /usr/local/bin (the default for Ubuntu 14.04).
I tried the answers to this question, but I still get the standard usr/local/ as my CMAKE_INSTALL_PREFIX when I check CMakeCache.txt.
The only working solution I have is to do
install(TARGETS my_exe DESTINATION "${CMAKE_SOURCE_DIR}/bin/")
but this then removes the user's ability to specify where the bin directory to install is.
tl;dr I would like make install to automatically install to ${CMAKE_SOURCE_DIR} by default, rather than /usr/local/.
CMake developers suggest to use given pattern for change default value of CMAKE_INSTALL_PREFIX inside CMakeLists.txt:
# Use this snippet *after* PROJECT(xxx):
IF(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
SET(CMAKE_INSTALL_PREFIX <path> CACHE PATH <comment> FORCE)
ENDIF(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
Using that approach
# Use this snippet *before* PROJECT(xxx):
SET(CMAKE_INSTALL_PREFIX <path> CACHE PATH <comment>)
is not recommended:
.. solution depends on the implementation details of the PROJECT command and is very fragile since it works "accidentally" for some versions of CMake. I don't consider it to be an option at all.
I'm trying to get a cross-plattform build system working using CMake. Now the software has a few dependencies. I compiled them myself and installed them on my system.
Some example files which got installed:
-- Installing: /usr/local/share/SomeLib/SomeDir/somefile
-- Installing: /usr/local/share/SomeLib/SomeDir/someotherfile
-- Installing: /usr/local/lib/SomeLib/somesharedlibrary
-- Installing: /usr/local/lib/SomeLib/cmake/FindSomeLib.cmake
-- Installing: /usr/local/lib/SomeLib/cmake/HelperFile.cmake
Now CMake has a find_package() which opens a Find*.cmake file and searches after the library on the system and defines some variables like SomeLib_FOUND etc.
My CMakeLists.txt contains something like this:
set(CMAKE_MODULE_PATH "/usr/local/lib/SomeLib/cmake/;${CMAKE_MODULE_PATH}")
find_package(SomeLib REQUIRED)
The first command defines where CMake searches after the Find*.cmake and I added the directory of SomeLib where the FindSomeLib.cmake can be found, so find_package() works
as expected.
But this is kind of weird because one of the reasons why find_package() exists is to get away from non-cross-plattform hard coded paths.
How is this usually done? Should I copy the cmake/ directory of SomeLib into my project and set the CMAKE_MODULE_PATH relatively?
Command find_package has two modes: Module mode and Config mode. You are trying to
use Module mode when you actually need Config mode.
Module mode
Find<package>.cmake file located within your project. Something like this:
CMakeLists.txt
cmake/FindFoo.cmake
cmake/FindBoo.cmake
CMakeLists.txt content:
list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/cmake")
find_package(Foo REQUIRED) # FOO_INCLUDE_DIR, FOO_LIBRARIES
find_package(Boo REQUIRED) # BOO_INCLUDE_DIR, BOO_LIBRARIES
include_directories("${FOO_INCLUDE_DIR}")
include_directories("${BOO_INCLUDE_DIR}")
add_executable(Bar Bar.hpp Bar.cpp)
target_link_libraries(Bar ${FOO_LIBRARIES} ${BOO_LIBRARIES})
Note that CMAKE_MODULE_PATH has high priority and may be usefull when you need to rewrite standard Find<package>.cmake file.
Config mode (install)
<package>Config.cmake file located outside and produced by install
command of other project (Foo for example).
foo library:
> cat CMakeLists.txt
cmake_minimum_required(VERSION 2.8)
project(Foo)
add_library(foo Foo.hpp Foo.cpp)
install(FILES Foo.hpp DESTINATION include)
install(TARGETS foo DESTINATION lib)
install(FILES FooConfig.cmake DESTINATION lib/cmake/Foo)
Simplified version of config file:
> cat FooConfig.cmake
add_library(foo STATIC IMPORTED)
find_library(FOO_LIBRARY_PATH foo HINTS "${CMAKE_CURRENT_LIST_DIR}/../../")
set_target_properties(foo PROPERTIES IMPORTED_LOCATION "${FOO_LIBRARY_PATH}")
By default project installed in CMAKE_INSTALL_PREFIX directory:
> cmake -H. -B_builds
> cmake --build _builds --target install
-- Install configuration: ""
-- Installing: /usr/local/include/Foo.hpp
-- Installing: /usr/local/lib/libfoo.a
-- Installing: /usr/local/lib/cmake/Foo/FooConfig.cmake
Config mode (use)
Use find_package(... CONFIG) to include FooConfig.cmake with imported target foo:
> cat CMakeLists.txt
cmake_minimum_required(VERSION 2.8)
project(Boo)
# import library target `foo`
find_package(Foo CONFIG REQUIRED)
add_executable(boo Boo.cpp Boo.hpp)
target_link_libraries(boo foo)
> cmake -H. -B_builds -DCMAKE_VERBOSE_MAKEFILE=ON
> cmake --build _builds
Linking CXX executable Boo
/usr/bin/c++ ... -o Boo /usr/local/lib/libfoo.a
Note that imported target is highly configurable. See my answer.
Update
Example
If you are running cmake to generate SomeLib yourself (say as part of a superbuild), consider using the User Package Registry. This requires no hard-coded paths and is cross-platform. On Windows (including mingw64) it works via the registry. If you examine how the list of installation prefixes is constructed by the CONFIG mode of the find_packages() command, you'll see that the User Package Registry is one of elements.
Brief how-to
Associate the targets of SomeLib that you need outside of that external project by adding them to an export set in the CMakeLists.txt files where they are created:
add_library(thingInSomeLib ...)
install(TARGETS thingInSomeLib Export SomeLib-export DESTINATION lib)
Create a XXXConfig.cmake file for SomeLib in its ${CMAKE_CURRENT_BUILD_DIR} and store this location in the User Package Registry by adding two calls to export() to the CMakeLists.txt associated with SomeLib:
export(EXPORT SomeLib-export NAMESPACE SomeLib:: FILE SomeLibConfig.cmake) # Create SomeLibConfig.cmake
export(PACKAGE SomeLib) # Store location of SomeLibConfig.cmake
Issue your find_package(SomeLib REQUIRED) commmand in the CMakeLists.txt file of the project that depends on SomeLib without the "non-cross-platform hard coded paths" tinkering with the CMAKE_MODULE_PATH.
When it might be the right approach
This approach is probably best suited for situations where you'll never use your software downstream of the build directory (e.g., you're cross-compiling and never install anything on your machine, or you're building the software just to run tests in the build directory), since it creates a link to a .cmake file in your "build" output, which may be temporary.
But if you're never actually installing SomeLib in your workflow, calling EXPORT(PACKAGE <name>) allows you to avoid the hard-coded path. And, of course, if you are installing SomeLib, you probably know your platform, CMAKE_MODULE_PATH, etc, so #user2288008's excellent answer will have you covered.
How is this usually done? Should I copy the cmake/ directory of SomeLib into my project and set the CMAKE_MODULE_PATH relatively?
If you don't trust CMake to have that module, then - yes, do that - sort of: Copy the find_SomeLib.cmake and its dependencies into your cmake/ directory. That's what I do as a fallback. It's an ugly solution though.
Note that the FindFoo.cmake modules are each a sort of a bridge between platform-dependence and platform-independence - they look in various platform-specific places to obtain paths in variables whose names is platform-independent.
You don't need to specify the module path per se. CMake ships with its own set of built-in find_package scripts, and their location is in the default CMAKE_MODULE_PATH.
The more normal use case for dependent projects that have been CMakeified would be to use CMake's external_project command and then include the Use[Project].cmake file from the subproject. If you just need the Find[Project].cmake script, copy it out of the subproject and into your own project's source code, and then you won't need to augment the CMAKE_MODULE_PATH in order to find the subproject at the system level.
CMake cannot find my Eigen3 package. I set an environment variable called
EIGEN3_INCLUDE_DIR
pointing to the path where FindEigen3.cmake is.
Then in the CMakelists.txt I wrote:
find_package( Eigen3 REQUIRED )
include_directories( EIGEN3_INCLUDE_DIR )
I get next message of error:
CMake Error at C:/Program Files (x86)/CMake 2.8/share/cmake-2.8/Modules/FindPackageHandleStandardArgs.cmake:91 (MESSAGE):
Could NOT find Eigen3 (missing: EIGEN3_INCLUDE_DIR EIGEN3_VERSION_OK)
(Required is at least version "2.91.0")
Call Stack (most recent call first):
C:/Program Files (x86)/CMake 2.8/share/cmake-2.8/Modules/FindPackageHandleStandardArgs.cmake:252 (_FPHSA_FAILURE_MESSAGE)
C:/Program Files (x86)/CMake 2.8/share/cmake-2.8/Modules/FindEigen3.cmake:76 (find_package_handle_standard_args)
test/test_quaternion/CMakeLists.txt:25 (find_package)
Any idea on what I am missing or doing wrong?
Since Eigen3 is completely header only, all you ever need is the path to the include directory. And this one, you are already defining manually anyway. So there is no real need for a FindEigen3.cmake or FIND_PACKAGE call.
Simply use
INCLUDE_DIRECTORIES ( "$ENV{EIGEN3_INCLUDE_DIR}" )
or
SET( EIGEN3_INCLUDE_DIR "$ENV{EIGEN3_INCLUDE_DIR}" )
IF( NOT EIGEN3_INCLUDE_DIR )
MESSAGE( FATAL_ERROR "Please point the environment variable EIGEN3_INCLUDE_DIR to the include directory of your Eigen3 installation.")
ENDIF()
INCLUDE_DIRECTORIES ( "${EIGEN3_INCLUDE_DIR}" )
A few notes:
If you want to access the content of a CMake variable, make sure to use ${...}
$ENV{....} accesses environment variables.
The second example will stop with an error if the environment variable is not set (and, thus, EIGEN3_INCLUDE_DIR cmake variable is empty)
Be careful to use quotation marks around (evaluated) variables if they could contain whitespace. Otherwise, CMake will interpret it as a list.
If you want to use custom find modules, make sure to either place them in you CMake installation or, as #Fraser pointed out above, make sure to point CMAKE_MODULE_PATH to the directory where it is. Not sure, but it could be that CMake checks the current directory as well automatically (where your CMakeLists.txt resides. Anyhow, setting EIGEN3_INCLUDE_DIR is totally unrelated to the location of FindEigen3.cmake
However, it could be that your FindEigen3 script evaluates this variable to determine the location of your Eigen3 installation.
Alternatively, self-built CMake-based projects often provide a <PackageName>Config.cmake. If you point a variable called <PackageName>_DIR to the directory containing this file, you can use FIND_PACKAGE( <PackageName> ...) as normal. See documentation of FIND_PACKAGE for details.
Eigen >= 3.3 has direct CMake integration, so it seems yours isn't set up correctly.
Assume Eigen has been installed to /opt/eigen/3.3 with default settings. Append or prepend the the location /opt/eigen/3.3 to the environment variable CMAKE_PREFIX_PATH e.g in bash:
export CMAKE_PREFIX_PATH="$CMAKE_PREFIX_PATH:/opt/eigen/3.3"
Then CMake should pick it up.
If you are writing your own CMakeLists.txt that uses Eigen I suggest using code like this:
find_package (Eigen3 3.3 REQUIRED)
add_executable (example example.cpp)
target_link_libraries (example Eigen3::Eigen)
You should not use include_directories since CMake 3 was released -- the targets approach should be preferred whenever available.
First, make sure Eigen is properly installed. Refer to the INSTALL file that comes with the tarball.
Second, copy the cmake/FindEigen3.cmake file from the tarball to the directory containing your CMakeLists.txt.
In your CMakeLists.txt add:
set(CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR})
find_package(Eigen3 REQUIRED)
include_directories(${EIGEN3_INCLUDE_DIR})
Now you should be able to do e.g. #include <Eigen/Core>.
All of this comes (mostly) from this source.
This approach has the advantage over e.g. include_directories("$ENV{EIGEN3_INCLUDE_DIR}") that it the uses CMake's standard mechanism for finding external dependencies, making it easier for someone else (or your future self) to pick up the project, possibly on another platform.
(However, it would be nice if Eigen itself installed an EigenConfig.cmake file, making it accessible through the find_package mechanism without any extra paths.)
I found another solution here (which referred to here) which uses the pkg-config file :
find_package(PkgConfig)
pkg_search_module(Eigen3 REQUIRED eigen3)
As a detailed explanation of the note 7 from the top answer of Johannes. By using the "Config mode" rather than "Module mode" of CMake find_packate(), only writing
find_package( Eigen3 REQUIRED )
include_directories( EIGEN3_INCLUDE_DIR )
in CMakeLists.txt is enough.
Please refer to the INSTALL guidance text file contained in the eigen source code directory (eg. extracted from eigen-3.3.7.tar.gz downloaded from official website), which said:
Method 2. Installing using CMake
********************************
Let's call this directory 'source_dir' (where this INSTALL file is).
Before starting, create another directory which we will call 'build_dir'.
Do:
cd build_dir
cmake source_dir
make install
The "make install" step may require administrator privileges.
You can adjust the installation destination (the "prefix")
by passing the -DCMAKE_INSTALL_PREFIX=myprefix option to cmake, as is
explained in the message that cmake prints at the end.
Just like installing usual CMake projects to your machine.
The difference from directly including the /usr/include/eigne3 or /usr/local/include/eigen3 directory is that, a configuration directory called eigen3/cmake will also be installed to /usr/share or usr/local/share. This configuration directory contains the Eigen3Config.cmake file, which can automatically be found by CMake to locate the eigen3 directory.
If you have not added Eigen Library to environment variable then do the following in CMakeLists.txt:
cmake_minimum_required(VERSION 3.9)
project(ProjectName)
set(CMAKE_CXX_STANDARD 11)
# set EIGEN_DIR variable to Eigen Library Path
set(EIGEN_DIR "C:\\Eigendir\\Eigen")
# include the directory
include_directories(${EIGEN_DIR})
add_executable(ProjectName main.cpp)
target_link_libraries(ProjectName ${EIGEN_DIR})
Another simple way that doesn't require adding an environment variable is to simply find eigen with the cmake find_path function https://cmake.org/cmake/help/v3.6/command/find_path.html. The example code finds the directory "Eigen" in paths "/usr/include/" and "/usr/local/include" with an additional search in subdirectory "eigen3".
find_path(EIGEN3_INCLUDE_DIRS "Eigen" paths "/usr/include" "/usr/local/include" path_suffixes "eigen3")
message(${EIGEN3_INCLUDE_DIRS})
if ( NOT EIGEN3_INCLUDE_DIRS )
message(FATAL_ERROR "CMake variable EIGEN3_INCLUDE_DIRS not found.")
endif()
include_directories ( "${EIGEN3_INCLUDE_DIRS}" )
You could try setting the CMAKE_MODULE_PATH to the location of Eigen subdirectory named "cmake":
cmake . -DCMAKE_MODULE_PATH=<Eigen root dir>/cmake/
I had a similar problem when run cmake .. && make on Google Colab on a project clone from github. I fixed it by editing CMakeLists.txt file and adding this line to it:
set(EIGEN3_INCLUDE_DIR "/usr/include/eigen3")
As you can see, my eigen3 was in /usr/include/eigen3 path (and I had installed it using !sudo apt-get install build-essential cmake libeigen3-dev)
When installing on Kubuntu 20.04 following steps from INSTALL:
Do:
cd build_dir
cmake source_dir
make install
using -DCMAKE_INSTALL_PREFIX=/usr/local/eigen-3.4.0 and sudo
FindEigen3.cmake is not installed. However, using
set(Eigen3_DIR "/usr/local/eigen/share/eigen3/cmake")
seem to work. FindEigen3.cmake is in the build directory
but it is not copied to the installation directory tree.
This worked:
Changed c++11 to c++14
Changed find_package(Eigen3 QUIET) to find_package(Eigen3 CONFIG)
Another simple way is:
if the Eigen library is in /opt/eigen/3.3/Eigen
include_directories(/opt/eigen/3.3)
which is equivalent to what Jai suggested
set(EIGEN_DIR "/opt/eigen/3.3")
include_directories(${EIGEN_DIR})
You need to read official documentation:
Click here
After install Eigen from tar and compile it correctly.
CMakeLists.txt will looks like this:
find_package(Eigen3 3.3 REQUIRED NO_MODULE)
add_executable(${PROJECT_NAME} something.cpp)
target_link_libraries(${PROJECT_NAME} Eigen3::Eigen)
It will be fine work.
I have a CMake project where I am using a library and now I want to test my code with a different version of that library. I can set INCLUDE_DIRECTORIES (and possibly later also linking) in the below example. But because I only want to do this temporarily, I'd like to manually set this path with ccmake/cmake-gui.
How do I do this?
project(min_example)
cmake_minimum_required(VERSION 2.8)
find_package(OpenCV REQUIRED)
# Without the following line please:
INCLUDE_DIRECTORIES("/home/me/src/opencv/install/include")
add_executable(min_example main.cpp)
target_link_libraries(min_example ${OpenCV_LIBS})
This should be possible by setting the CMAKE_PREFIX_PATH variable upon configuring your build. In your project directory generate a test_build directory and run:
mkdir test_build
cd test_build
cmake -DCMAKE_PREFIX_PATH=/home/me/src/opencv/install ..
Setting the CMAKE_PREFIX_PATH variable will make the find_package(OpenCV REQUIRED) command pick your OpenCV installation in /home/me/src/opencv and set the OpenCV_LIBS and OpenCV_INCLUDE_DIR variables accordingly.
Alternatively you can edit a CMakeCache.txt file of an existing build directory with the CMake GUI editor and add the CMAKE_PREFIX_PATH definition there. You have to re-configure your project then.
Using config in find_package will restrict search path to OpenCV_DIR. This will use the cmake config that opencv generates at build time to setup paths to include and libs
set(OpenCV_DIR "<cusompath>" CACHE PATH '' ${SHOULD_FORCE_CACHE})
find_package(OpenCV REQUIRED CONFIG)