ChatGPT解决这个技术问题 Extra ChatGPT

What is CMake equivalent of 'configure --prefix=DIR && make all install '?

I do cmake . && make all install. This works, but installs to /usr/local.

I need to install to a different prefix (for example, to /usr).

What is the cmake and make command line to install to /usr instead of /usr/local?

This is a great question for changing the install directory on the fly, but why is this such an apparently common need? From my perspective, the answer should be DON'T use a command line option, instead edit the base CMakeLists.txt so you can set it and forget it. I'm not saying there isn't a common use case for changing the install directory on the fly -- clearly there is judging by the number of votes -- I'm just fairly new to CMake and curious when this problem comes up.
@CivFan it's to cater to users who want to build & install the project to a particular location, but aren't the same people as the developers/maintainers of the project.
@CivFan So as a maintainer, its not uncommon for me to test my make install to a temporary path to make sure everything that needs to be installed, got installed to the right location without messing up my development machine. Just one example. Another case is cross-compiling for another architecture.
@CivFan: I need this because I want to build an RPM package. If I would need to change the CMakeLists.txt, then I need to patch the original source. Just having a command line option allows me to get the paths right in the Fedora spec file.
@CivFan (and others reading this) FYI, it's generally considered a bad idea to edit the CMakeLists.txt file if you're just building and installing software - overriding/setting variables from command line or initial cache file, etc. is the preferred "consumer" way of setting options.

M
Marcus D. Hanwell

You can pass in any CMake variable on the command line, or edit cached variables using ccmake/cmake-gui. On the command line,

cmake -DCMAKE_INSTALL_PREFIX:PATH=/usr . && make all install

Would configure the project, build all targets and install to the /usr prefix. The type (PATH) is not strictly necessary, but would cause the Qt based cmake-gui to present the directory chooser dialog.

Some minor additions as comments make it clear that providing a simple equivalence is not enough for some. Best practice would be to use an external build directory, i.e. not the source directly. Also to use more generic CMake syntax abstracting the generator.

mkdir build && cd build && cmake -DCMAKE_INSTALL_PREFIX:PATH=/usr .. && cmake --build . --target install --config Release

You can see it gets quite a bit longer, and isn't directly equivalent anymore, but is closer to best practices in a fairly concise form... The --config is only used by multi-configuration generators (i.e. MSVC), ignored by others.


Wondering what :PATH is? It's useful for cmake-gui, helping to choose the widget for that variable. See doc in linux.die.net/man/1/cmake-gui (set section)
They provide hints to the CMake GUI as stated, everything in CMake is effectively a string, but setting PATH, FILEPATH, STRING, BOOL etc help the GUI to present a more appropriate widget.
You can also use: "cmake --build --target install ." instead of make.
What is the dot for after /usr? /usr .
@bodacydo location of the folder with CMakeLists.txt we're generating from.
C
Community

The ":PATH" part in the accepted answer can be omitted. This syntax may be more memorable:

cmake -DCMAKE_INSTALL_PREFIX=/usr . && make all install

...as used in the answers here.


A
Alexander

Note that in both CMake and Autotools you don't always have to set the installation path at configure time. You can use DESTDIR at install time (see also here) instead as in:

make DESTDIR=<installhere> install

See also this question which explains the subtle difference between DESTDIR and PREFIX.

This is intended for staged installs and to allow for storing programs in a different location from where they are run e.g. /etc/alternatives via symbolic links.

However, if your package is relocatable and doesn't need any hard-coded (prefix) paths set via the configure stage you may be able to skip it. So instead of:

cmake -DCMAKE_INSTALL_PREFIX=/usr . && make all install

you would run:

cmake . && make DESTDIR=/usr all install

Note that, as user7498341 points out, this is not appropriate for cases where you really should be using PREFIX.


I like showing the use of DESTDIR. But actually this is wrong. You should refer to the cmake docs cmake.org/cmake/help/v3.0/variable/CMAKE_INSTALL_PREFIX.html ... make DESTDIR=/home/john install which will install the concerned software using the installation prefix, e.g. “/usr/local” prepended with the DESTDIR value which finally gives “/home/john/usr/local”.
I don't think that's contradictory. If your package is relocatable you don't need CMAKE_INSTALL_PREFIX, or rather you can choose either method. If it isn't you do because CMAKE_INSTALL_PREFIX will be baked in somewhere at build time.
if you know that your generator is Makefile... I prefer cmake --build build --target install -- DESTDIR=/usr note: this should also work with Ninja generator (rules seems to contains $ENV{DESTDIR})
@Joakim as much as I'd like to use CMAKE_INSTALL_PREFIX, doing so embedded the install path in the compiled files. As it happens, I was merely building a .rpm package, so that wouldn't do. DESTDIR worked like a charm for getting things into buildroot.
P
Peter Mortensen

The way I build CMake projects cross platform is the following:

/project-root> mkdir build
/project-root> cd build
/project-root/build> cmake -G "<generator>" -DCMAKE_INSTALL_PREFIX=stage ..
/project-root/build> cmake --build . --target=install --config=Release

The first two lines create the out-of-source build directory

The third line generates the build system specifying where to put the installation result (which I always place in ./project-root/build/stage - the path is always considered relative to the current directory if it is not absolute)

The fourth line builds the project configured in . with the buildsystem configured in the line before. It will execute the install target which also builds all necessary dependent targets if they need to be built and then copies the files into the CMAKE_INSTALL_PREFIX (which in this case is ./project-root/build/stage. For multi-configuration builds, like in Visual Studio, you can also specify the configuration with the optional --config flag.

The good part when using the cmake --build command is that it works for all generators (i.e. makefiles and Visual Studio) without needing different commands.

Afterwards I use the installed files to create packages or include them in other projects...


Thanks for the step by step explanation! IMO this is the only way, otherwise the whole point of cmake (platform independence) is discarded...
did you forget to include path to sources (../) in line 3? BTW this should be the accepted answer.
LIne 3 should be cmake -G "<generator>" -DCMAKE_INSTALL_PREFIX=stage ..
As an additional note, pragmatically, people use make -j $(nproc), to specify the number of build threads, do cmake --build . --target=install --config=Release -- -j 8 for Makefile generator or cmake --build . --target=install --config=Release -- /m:8 for Visual Studio generator with 8 threads. Actually, you can pass any commandline parameters after --
@MrRedstoner -j is not a flag for cmake, all flags come after -- is passing to the underlying build system...
E
ExaltedBagel

Starting with CMake 3.15, the correct way of achieving this would be using:

cmake --install <dir> --prefix "/usr"

Official Documentation


"supported" doesn't mean "correct" -- this has its uses but since building and installing happens more often than generating the build system, it's often safer to just set the env var when generating the build system. both are "correct" depending on use case.
u
user7498341

Regarding Bruce Adams answer:

Your answer creates dangerous confusion. DESTDIR is intended for installs out of the root tree. It allows one to see what would be installed in the root tree if one did not specify DESTDIR. PREFIX is the base directory upon which the real installation is based.

For example, PREFIX=/usr/local indicates that the final destination of a package is /usr/local. Using DESTDIR=$HOME will install the files as if $HOME was the root (/). If, say DESTDIR, was /tmp/destdir, one could see what 'make install' would affect. In that spirit, DESTDIR should never affect the built objects.

A makefile segment to explain it:

install:
    cp program $DESTDIR$PREFIX/bin/program

Programs must assume that PREFIX is the base directory of the final (i.e. production) directory. The possibility of symlinking a program installed in DESTDIR=/something only means that the program does not access files based upon PREFIX as it would simply not work. cat(1) is a program that (in its simplest form) can run from anywhere. Here is an example that won't:

prog.pseudo.in:
    open("@prefix@/share/prog.db")
    ...

prog:
    sed -e "s/@prefix@/$PREFIX/" prog.pseudo.in > prog.pseudo
    compile prog.pseudo

install:
    cp prog $DESTDIR$PREFIX/bin/prog
    cp prog.db $DESTDIR$PREFIX/share/prog.db

If you tried to run prog from elsewhere than $PREFIX/bin/prog, prog.db would never be found as it is not in its expected location.

Finally, /etc/alternatives really does not work this way. There are symlinks to programs installed in the root tree (e.g. vi -> /usr/bin/nvi, vi -> /usr/bin/vim, etc.).


This answer might be better placed as an answer to stackoverflow.com/questions/11307465/destdir-and-prefix-of-make
F
Florian Wolters

It is considered bad practice to invoke the actual build system (e.g. via the make command) if using CMake. It is highly recommended to do it like this:

Configure + Generation stages: cmake -S foo -B _builds/foo/debug -G "Unix Makefiles" -D CMAKE_BUILD_TYPE:STRING=Debug -D CMAKE_DEBUG_POSTFIX:STRING=d -D CMAKE_INSTALL_PREFIX:PATH=/usr Build and Install stages: cmake --build _builds/foo/debug --config Debug --target install

When following this approach, the generator can be easily switched (e.g. -G Ninja for Ninja) without having to remember any generator-specific commands.

Note that the CMAKE_BUILD_TYPE variable is only used by single-config generators and the --config argument of the build command is only used by multi-config generators.


The answer could have been better if explanation was provided to all the arguments used and why they are used. Particularly, what is the point of the --config argument?
Don't use the undocumented -H flag. The officially supported replacement is -S
@DmitryKabanov CMake supports many generators. However, there are two classes - single configuration ones (like Make and Ninja) and multi-configuration ones (like Visual Studio). The first class relies on CMAKE_BUILD_TYPE established during configuration. The second class relies on --config argument provided during building (and then also installing). This is because with multi-configuration generators, unsurprisingly, you can build many types out of single CMake configuration.
I've improved my answer. Thanks for the feedback.
T
Tachi

Starting with CMake 3.21 you can use the --install-prefix option instead of manually setting CMAKE_INSTALL_PREFIX.

The modern equivalent of configure --prefix=DIR && make all install would now be:

cmake -S . -B build --install-prefix=DIR
cmake --build build
cmake --install build