[CMake] What is the purpose of INSTALL_DIR in ExternalProject_Add command?

[Cedric Doucet]

Hello Iosif and David,

thank you for your answer.
I now understand how it works.
But I still don't understand the purpose of INSTALL_DIR.
Do you know an example when this variable is useful?

Cédric




----- Mail original -----
> De: "Iosif Neitzke" <iosif.neitzke+cmake at gmail.com>
> À: cmake at cmake.org
> Envoyé: Jeudi 9 Avril 2015 12:54:28
> Objet: Re: [CMake] What is the purpose of INSTALL_DIR in	ExternalProject_Add command?
> 
> Install Step
> The INSTALL_DIR is underneath the calling project’s binary directory.
> Use INSTALL_DIR to specify a different location. Note that in addition
> to setting INSTALL_DIR, you also have to pass -DCMAKE_INSTALL_PREFIX
> or --prefix to the CMake or configure command. It is not used
> automatically in the configure step since not all projects follow this
> convention.
> 
> From
> http://www.kitware.com/media/html/BuildingExternalProjectsWithCMake2.8.html
> 
> On Thu, Apr 9, 2015 at 5:44 AM, David Cole via CMake <cmake at cmake.org> wrote:
> > You need to tell eigen where to install, probably as an argument to its
> > configure step. If it builds with CMake, you can use:
> >
> >     -DCMAKE_INSTALL_PREFIX=<INSTALL_DIR>
> >
> > as one of the CMake args. If it has a non-CMake configure step, you'll have
> > to call that and pass in <INSTALL_DIR> as an argument.
> >
> >
> > HTH,
> > David C.
> >
> >
> > On Thursday, April 9, 2015, Cedric Doucet <cedric.doucet at inria.fr> wrote:
> >>
> >>
> >> Hello!
> >>
> >> I try to download, extract, configure, build and install a library with
> >> CMake.
> >> My CMakeLists.txt contains the following lines:
> >>
> >> cmake_minimum_required (VERSION 2.6)
> >> project (example CXX)
> >> set(CMAKE_VERBOSE_MAKEFILE ON)
> >> include(ExternalProject)
> >> include(ProcessorCount)
> >> ProcessorCount(N)
> >> if(NOT N EQUAL 0)
> >>   set(CMAKE_BUILD_FLAGS -j${N})
> >> endif()
> >> ExternalProject_Add(eigen
> >>                     PREFIX third_party
> >>                     DOWNLOAD_DIR third_party/eigen/download
> >>                     SOURCE_DIR third_party/eigen/src
> >>                     BINARY_DIR third_party/eigen/build
> >>                     INSTALL_DIR third_party/eigen/install
> >>                     DOWNLOAD_COMMAND wget
> >> http://bitbucket.org/eigen/eigen/get/3.2.4.tar.gz && tar xvzf 3.2.4.tar.gz
> >> -C ../src --strip-components=1
> >>                    )
> >>
> >> In this example, the installation step fails with the following error
> >> message:
> >>
> >> CMake Error at cmake_install.cmake:38 (FILE):
> >>   file cannot create directory: /usr/local/include/eigen3.  Maybe need
> >>   administrative privileges.
> >>
> >> It means that the value of INSTALL_DIR is not taken into account during
> >> the configuration process.
> >>
> >> Why? What am I do wrong?
> >>
> >> Thank you very much for your help.
> >>
> >> Best regards,
> >>
> >> Cédric Doucet
> >> --
> >>
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> Powered by www.kitware.com
> 
> Please keep messages on-topic and check the CMake FAQ at:
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> 
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> 
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