CMAKE_INSTALL_PREFIX

Install directory used by :command:install.

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

This variable defaults as follows:

.. versionadded:: 3.29

If the :envvar:CMAKE_INSTALL_PREFIX environment variable is set, its value is used as default for this variable.
c:/Program Files/${PROJECT_NAME} on Windows.
/usr/local on UNIX platforms.

See :variable:CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT for how a project might choose its own default.

On UNIX one can use the DESTDIR mechanism in order to relocate the whole installation to a staging area. See the :envvar:DESTDIR environment variable for more information.

The installation prefix is also added to :variable:CMAKE_SYSTEM_PREFIX_PATH so that :command:find_package, :command:find_program, :command:find_library, :command:find_path, and :command:find_file will search the prefix for other software. This behavior can be disabled by setting the :variable:CMAKE_FIND_NO_INSTALL_PREFIX to TRUE before the first :command:project invocation.

.. note::

Use the :module:GNUInstallDirs module to provide GNU-style options for the layout of directories within the installation.

The CMAKE_INSTALL_PREFIX may be defined when configuring a build tree to set its installation prefix. Or, when using the :manual:cmake(1) command-line tool's :option:--install <cmake --install> mode, one may specify a different prefix using the :option:--prefix <cmake--install --prefix> option:

.. code-block:: shell

cmake --install . --prefix /my/install/prefix

.. note::

When the project is using the :module:GNUInstallDirs module, there are some :ref:special cases <GNUInstallDirs special cases> that are evaluated based on the value of the :variable:CMAKE_INSTALL_PREFIX variable during the configuration phase. The results persist even if an alternative :option:--prefix <cmake--install --prefix> option is used during installation.