FindPkgConfig

A pkg-config module for CMake.

Finds the pkg-config executable and provides commands to use it in CMake:

find_package(PkgConfig [<version>] [QUIET] [REQUIRED] [...])

pkg-config is a command-line program for configuring build dependency information. Initially developed by FreeDesktop, it is also available in several implementations, such as pkgconf, u-config, and similar. It reads package data from the so-called PC metadata files (<module-name>.pc) that may come installed with packages. This module is a wrapper around the pkg-config command-line executable.

結果變數

該模組定義了以下變數：

PkgConfig_FOUND

在 3.3 版被加入.

Boolean indicating whether the (requested version of) pkg-config executable was found.

PkgConfig_VERSION

在 4.2 版被加入.

The version of pkg-config that was found.

PKG_CONFIG_EXECUTABLE

The pathname of the pkg-config program.

PKG_CONFIG_ARGN

在 3.22 版被加入.

A list of arguments to pass to pkg-config.

Both PKG_CONFIG_EXECUTABLE and PKG_CONFIG_ARGN are initialized by the module, but may be overridden by the user. See Hints for how these variables are initialized.

命令

This module provides the following commands, if pkg-config is found:

pkg_check_modules

Checks for all the given modules, setting a variety of result variables in the calling scope:

pkg_check_modules(
  <prefix>
  [QUIET]
  [REQUIRED]
  [NO_CMAKE_PATH]
  [NO_CMAKE_ENVIRONMENT_PATH]
  [IMPORTED_TARGET [GLOBAL]]
  <module-spec> [<module-spec>...]
)

The arguments are:

<prefix>

Prefix string prepended to result variables for the specified modules.

QUIET

When this argument is given, no status messages will be printed.

REQUIRED

When this argument is given, the command will fail with an error if any of the specified module(s) could not be found.

NO_CMAKE_PATH, NO_CMAKE_ENVIRONMENT_PATH

在 3.3 版被加入.

The CMAKE_PREFIX_PATH, CMAKE_FRAMEWORK_PATH, and CMAKE_APPBUNDLE_PATH cache and environment variables will be added to the pkg-config search path. The NO_CMAKE_PATH and NO_CMAKE_ENVIRONMENT_PATH arguments disable this behavior for the cache variables and environment variables respectively. The PKG_CONFIG_USE_CMAKE_PREFIX_PATH variable set to FALSE disables this behavior globally.

IMPORTED_TARGET [GLOBAL]

在 3.7 版被加入.

This argument will create an imported target named PkgConfig::<prefix> that can be passed directly as an argument to target_link_libraries(). It will encapsulate usage requirements for all specified modules <module-spec>... at once.

GLOBAL

在 3.13 版被加入.

This argument is used together with IMPORTED_TARGET and will make the imported target available in global scope.

在 3.15 版被加入: Non-library linker options reported by pkg-config are stored in the INTERFACE_LINK_OPTIONS target property.

在 3.18 版的變更: Include directories specified with -isystem are stored in the INTERFACE_INCLUDE_DIRECTORIES target property. Previous versions of CMake left them in the INTERFACE_COMPILE_OPTIONS property.

<module-spec>

Each <module-spec> can be either a bare module name (as defined in its PC metadata file name <module-name>.pc) or it can be a module name with a version constraint (operators =, <, >, <= and >= are supported). The following are examples for a module named foo with various constraints:

  • foo matches any version.

  • foo<2 only matches versions before 2.

  • foo>=3.1 matches any version from 3.1 or later.

  • foo=1.2.3 requires that foo must be exactly version 1.2.3.

結果變數

The following variables may be set upon return. Two sets of values exist: One for the common case (<XXX> = <prefix>) and another for the information pkg-config provides when called with the --static option (<XXX> = <prefix>_STATIC).

<XXX>_FOUND

Boolean variable set to 1 if module(s) exist.

<XXX>_LIBRARIES

A list of only the libraries (without the -l).

<XXX>_LINK_LIBRARIES

The libraries and their absolute paths.

<XXX>_LIBRARY_DIRS

The paths of the libraries (without the -L).

<XXX>_LDFLAGS

All required linker flags.

<XXX>_LDFLAGS_OTHER

All other linker flags.

<XXX>_INCLUDE_DIRS

The -I preprocessor flags (without the -I).

<XXX>_CFLAGS

All required cflags.

<XXX>_CFLAGS_OTHER

The other compiler flags.

All but <XXX>_FOUND may be a semicolon-separated list if the associated variable returned from pkg-config has multiple values.

在 3.18 版的變更: Include directories specified with -isystem are stored in the <XXX>_INCLUDE_DIRS variable. Previous versions of CMake left them in <XXX>_CFLAGS_OTHER.

There are some special variables whose prefix depends on the number of <module-spec> given. When there is only one <module-spec>, <YYY> will simply be <prefix>, but if two or more <module-spec> items are given, <YYY> will be <prefix>_<module-name>.

<YYY>_VERSION

The version of the module.

<YYY>_PREFIX

The prefix directory of the module.

<YYY>_INCLUDEDIR

The include directory of the module.

<YYY>_LIBDIR

The lib directory of the module.

在 3.8 版的變更: For any given <prefix>, pkg_check_modules() can be called multiple times with different parameters. Previous versions of CMake cached and returned the first successful result.

在 3.16 版的變更: If a full path to the found library can't be determined, but it's still visible to the linker, pass it through as -l<name>. Previous versions of CMake failed in this case.

pkg_search_module

Searches for the first successful match from one or more provided module specifications:

pkg_search_module(
  <prefix>
  [QUIET]
  [REQUIRED]
  [NO_CMAKE_PATH]
  [NO_CMAKE_ENVIRONMENT_PATH]
  [IMPORTED_TARGET [GLOBAL]]
  <module-spec> [<module-spec>...]
)

The behavior and arguments of this command are the same as pkg_check_modules(), except that rather than checking for all the specified modules, it searches for just the first successful match.

This command can be used, for example, when some package is known to have possible multiple <module-spec> on different platforms or versions for the same package.

結果變數

This command defines the same variables as described above with addition to:

<prefix>_MODULE_NAME

在 3.16 版被加入.

If a module is found, the <prefix>_MODULE_NAME variable will contain the name of the matching module. This variable can be used if the pkg_get_variable() command needs to be called with the <module-name> argument that was found by the pkg_search_module().

pkg_get_variable

在 3.4 版被加入.

Retrieves the value of a pkg-config variable and stores it in the result variable in the calling scope:

pkg_get_variable(
  <result-var>
  <module-name>
  <var-name>
  [DEFINE_VARIABLES <key>=<value>...]
)

The arguments are:

<result-var>

Name of the result variable that will contain the value of pkg-config variable. If pkg-config returns multiple values for the specified variable <var-name>, <result-var> will contain a semicolon-separated list.

<module-name>

Name of the module as defined in its PC metadata file name (<module-name>.pc).

<var-name>

The pkg-config variable name from the PC metadata file <module-name>.pc.

DEFINE_VARIABLES <key>=<value>...

在 3.28 版被加入.

Specify key-value pairs to redefine variables affecting the variable retrieved with pkg-config.

提示

This module accepts the following variables before calling find_package(PkgConfig) to influence this module's behavior:

ENV{PKG_CONFIG_PATH}

Environment variable that specifies additional paths in which pkg-config will search for its .pc files. The pkg-config tool by default uses this variable, while CMake also provides more common CMAKE_PREFIX_PATH variable to specify additional paths where to look for packages and their .pc files.

ENV{PKG_CONFIG}

在 3.1 版被加入.

Environment variable that can be set to the path of the pkg-config executable and can be used to initialize the PKG_CONFIG_EXECUTABLE variable, if it has not yet been set.

PKG_CONFIG_EXECUTABLE

This cache variable can be set to the path of the pkg-config executable. find_program() is called internally by the module with this variable.

在 3.22 版的變更: If the PKG_CONFIG environment variable is set, only the first argument is taken from it when using it as a hint.

PKG_CONFIG_ARGN

在 3.22 版被加入.

This cache variable can be set to a list of arguments to additionally pass to pkg-config if needed. If not provided, it will be initialized from the PKG_CONFIG environment variable, if set. The first argument in that environment variable is assumed to be the pkg-config program, while all remaining arguments after that are used to initialize PKG_CONFIG_ARGN. If no such environment variable is defined, PKG_CONFIG_ARGN is initialized to an empty string. The module does not update the variable once it has been set in the cache.

PKG_CONFIG_USE_CMAKE_PREFIX_PATH

在 3.1 版被加入.

Specifies whether pkg_check_modules() and pkg_search_module() should add the paths in the CMAKE_PREFIX_PATH, CMAKE_FRAMEWORK_PATH and CMAKE_APPBUNDLE_PATH cache and environment variables to the pkg-config search path.

If this variable is not set, this behavior is enabled by default if CMAKE_MINIMUM_REQUIRED_VERSION is 3.1 or later, disabled otherwise.

已棄用的變數

The following variables are provided for backward compatibility:

PKG_CONFIG_FOUND

在 4.2 版之後被棄用: Use PkgConfig_FOUND, which has the same value.

Boolean indicating whether the (requested version of) pkg-config executable was found.

PKG_CONFIG_VERSION_STRING

在 4.2 版之後被棄用: Use PkgConfig_VERSION, which has the same value.

The version of pkg-config that was found.

範例

Examples: Finding pkg-config

Finding pkg-config:

find_package(PkgConfig)

Finding pkg-config and making it required (if not found, processing stops with an error message):

find_package(PkgConfig REQUIRED)

Finding pkg-config quietly without printing status message as commonly used in find modules:

find_package(PkgConfig QUIET)

Examples: Using pkg_check_modules()

Checking for any version of glib2. If found, the output variable GLIB2_VERSION will hold the actual version found:

find_package(PkgConfig QUIET)

if(PkgConfig_FOUND)
  pkg_check_modules(GLIB2 glib-2.0)
endif()

The following example looks for at least version 2.10 of glib2. If found, the output variable GLIB2_VERSION will hold the actual version found:

find_package(PkgConfig QUIET)

if(PkgConfig_FOUND)
  pkg_check_modules(GLIB2 glib-2.0>=2.10)
endif()

The following example looks for both glib2-2.0 (at least version 2.10) and any version of gtk2+-2.0. Only if both are found will FOO be considered found. The FOO_glib-2.0_VERSION and FOO_gtk+-2.0_VERSION variables will be set to their respective found module versions.

find_package(PkgConfig QUIET)

if(PkgConfig_FOUND)
  pkg_check_modules(FOO glib-2.0>=2.10 gtk+-2.0)
endif()

The following example requires any version of xrender:

find_package(PkgConfig QUIET REQUIRED)
pkg_check_modules(XRENDER REQUIRED xrender)

Example output variables set by a successful call:

XRENDER_LIBRARIES=Xrender;X11
XRENDER_STATIC_LIBRARIES=Xrender;X11;pthread;Xau;Xdmcp

Example: Using pkg_search_module()

Searching for LibXml2 package, which might be provided with different module specifications (libxml-2.0 or libxml2):

find_package(PkgConfig QUIET)

if(PkgConfig_FOUND)
  pkg_search_module(BAR libxml-2.0 libxml2 libxml>=2)
endif()

Example: Creating Imported Target

In the following example an imported target is created from the module specifications to use in the project directly without using a find module. These imported targets can be used, for example, in cases, where package is known to support pkg-config on all supported platforms:

find_package(PkgConfig QUIET REQUIRED)
pkg_check_modules(GTK REQUIRED IMPORTED_TARGET gtk4>=4.14)
target_link_libraries(example PRIVATE PkgConfig::GTK)

Example: Using pkg_get_variable()

Retrieving the value of pkg-config variable girdir from the package Gobject:

find_package(PkgConfig QUIET)

if(PkgConfig_FOUND)
  pkg_get_variable(GI_GIRDIR gobject-introspection-1.0 girdir)
endif()

message(STATUS "${GI_GIRDIR}")

另請參見

  • The cmake_pkg_config() command for a modern and more advanced way to work with pkg-config in CMake without requiring pkg-config executable to be installed.

  • Find Modules for details how to write a find module.