Set installation prefix automatically to custom path if not explicitly specified on the command line
Solution 1
CMake sets the boolean variable CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT
if CMAKE_INSTALL_PREFIX
has not been explicitly specified and is initialized to its default setting. You can override it in the following way:
if (CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
set (CMAKE_INSTALL_PREFIX "${CMAKE_BINARY_DIR}/installed"
CACHE PATH "default install path" FORCE)
endif()
Solution 2
A few years ago, I wanted to attempt the same thing. Unfortunately I could never find a fully satisfactory solution. Instead, I chose to use a regex to check if CMAKE_INSTALL_PREFIX
matches the default.
E.g. on windows I use the following to create the install
dir in the build-directory:
if ( CMAKE_INSTALL_PREFIX MATCHES "^C:/Program Files" )
# Override to an "Install" directory in the current build-dir
message( STATUS " Install-prefix was at default -> forcing it to the build-dir" )
message( STATUS " 'set( CMAKE_INSTALL_PREFIX ${CMAKE_CURRENT_BINARY_DIR}/install )'" )
set( CMAKE_INSTALL_PREFIX ${CMAKE_CURRENT_BINARY_DIR}/install )
endif ( CMAKE_INSTALL_PREFIX MATCHES "^C:/Program Files" )
The biggest problem with this construct is that you can specify manually that CMake should install into C:\Program Files
. As I distribute my tool with an NSIS-installer this is not an issue (for me).
Perhaps you could try something similar on Unix.
Jeet
Updated on June 14, 2022Comments
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Jeet almost 2 years
For some internal tests, I would like the install prefix to default to a subdirectory of the build directory, unless explicitly overridden by the user. I know the user can specify a install prefix by:
$ cmake -DCMAKE_INSTALL_PREFIX=/foo/bar ..
But if the user does not specify this, it should default to, e.g.
${PWD}/installed
.The variable
CMAKE_INSTALL_PREFIX
is already set to/usr/local
, so I cannot just check to see if it unset/empty before setting it.My current solution is to add a custom switch that the user has to invoke to specify that the
CMAKE_INSTALL_PREFIX
variable gets respected:option(ENABLE_INSTALL_PREFIX "Install build targets to system (path given by '-DCMAKE_INSTALL_PREFIX' or '${CMAKE_INSTALL_PREFIX}' if not specified)." OFF) if ( ENABLE_INSTALL_PREFIX ) set (CMAKE_INSTALL_PREFIX installed CACHE PATH "Installation root") else() set (CMAKE_INSTALL_PREFIX installed CACHE PATH "Installation root" FORCE) endif()
My questions are:
(a) Are there any issues with the above, beyond the annoyance of the extra flag needing to be passed to CMake to get
CMAKE_INSTALL_PREFIX
to have an effect?(b) Is there a better, cleaner, more robust, more idiomatic and/or less annoying way to achieve the above?
Thanks.
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KarateSnowMachine over 9 yearsI wish I found this post a few days ago while I was pulling my hair out trying to get multiple ExternalProject dependencies to do the right thing. Thanks!
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thiagowfx over 7 yearsOn Unix one would use
"^/usr/local"
in the matching; or, even better,STREQUAL "/usr/local"
instead of a regular expression matching.