PKG-CONFIG(1) General Commands Manual PKG-CONFIG(1)

pkg-config — a system for configuring build dependency information

pkg-config [options] module ...

The pkg-config program retrieves configuration information related to the module arguments from pc(5) files installed on the system and prints parts of the retrieved information depending on the specified options. The most common use is printing the compiler and linker flags needed to build software that uses the libraries given by the module arguments.

The pc(5) files are searched for along a path constructed from the --with-path option, the PKG_CONFIG_PATH and PKG_CONFIG_LIBDIR environment variables, and some compiled-in default directories. The module arguments correspond to the file names, but without the .pc filename extension.

Several of the options cause immediate exit. If multiple of these options are given, only the option with the highest priority takes effect and those with lower priority are silently ignored. These options are, ordered by descending priority:

  1. No-module options: --relocate, --dump-personality, --about, --version, --help, --atleast-pkgconfig-version, --list-all, and --list-package-names: These options cause all arguments to be ignored.
  2. Argument-only options: --atleast-version, --exact-version, and --max-version: These options only inspect modules explicitly specified on the command line and do not look at dependencies.
  3. Limited-output options: --validate, --license, --uninstalled, and --env: These options perform dependency resolution, but exit after printing the information requested by the highest-priority option, ignoring other output options that may have been specified.

Several other options require at least one module argument, produce output, do not cause early exit, can be combined with each other, but override and disable all --cflags and --libs options:

  1. Single-module output options: --path, --print-variables, --variable: If any of these options is specified, only the first module argument is used, all other arguments are silently ignored, and no dependency resolution is attempted.
  2. Depth-one output options: --print-provides, --modversion, --print-requires, and --print-requires-private: If any of these options is specified, only modules explicitly specified on the command line are inspected and no dependency resolution is attempted.
  3. General output options: --simulate, --digraph, --solution, --fragment-tree: These options do not limit dependency resolution.

The most important output options --cflags and --libs can be combined with each other, but are overridden and ignored if any of the options listed above are specified.

The complete list of options is as follows:

Print the version number, the Copyright notice, and the license of the pkg-config program to standard output and exit. Most other options and all command line arguments are ignored.
=version
Exit with error if the requested version number is greater than the version number of the pkg-config program, or with success otherwise. Most other options and all command line arguments are ignored.
=version
Check the module arguments in the given order. Exit with error as soon as a module does not exist, and exit with success as soon as the version number of a module is greater than or equal to the requested version number. Exit with error if the version number of each module is less than the requested version number.
, --cflags-only-I, --cflags-only-other
Print all compiler flags required to compile against the module, or only the include path (-I) flags, or only the compiler flags that are not include path flags, respectively. These options imply --print-errors.
Print some non-fatal warning messages to standard error output that would otherwise silently be ignored. This option also implies --print-errors. If pkg-config was compiled without defining the preprocessor macro PKGCONF_LITE, this option also prints many debugging messages to standard error output.
Attempts to determine the prefix variable to use for CFLAGS and LIBS entry relocations. This is mainly useful for platforms where framework SDKs are relocatable, such as Windows.
=varname=value
Define varname as value. Variables are used in query output, and some modules' results may change based on the presence of a variable definition.
Dump the dependency resolver's solution as a graphviz ‘dot’ file. This can be used with graphviz to visualize module interdependencies. This option is only available if the preprocessor macro PKGCONF_LITE was not defined during compilation.
Disables the ‘define-prefix’ feature.
Disables the path relocation feature.
Print some default settings to standard output, in particular the default module search path that is used when PKG_CONFIG_LIBDIR is not defined, the default list of include paths that are filtered out when PKG_CONFIG_SYSTEM_INCLUDE_PATH is not defined, and the default list of library paths that are filtered out when PKG_CONFIG_SYSTEM_LIBRARY_PATH is not defined, and exit. Most other options and all command line arguments are ignored. This option is only available if the preprocessor macro PKGCONF_LITE was not defined during compilation.
=varname
Print the requested values as variable declarations in a similar format as the env(1) command.
Initialize the module search path from --with-path and PKG_CONFIG_PATH only, ignoring PKG_CONFIG_LIBDIR and the compiled-in default directories.
Print all error, warning, and debugging messages to standard output instead of to standard error output.
=version
Check the module arguments in the given order. Exit with error as soon as a module does not exist, and exit with success as soon as the version number of a module is exactly the requested version number. Exit with error if the version number of each module differs from the requested version number.
Exit with a non-zero exit status if the dependency resolver is unable to find all of the requested modules. This option is active by default and cannot be disabled. However, various other options cause pkg-config to exit and report success or failure before all arguments have been inspected.
=types
Filter the fragment lists for the specified types.
Print a usage summary on standard output and exit. Most other options and all command line arguments are ignored.
Ignore ‘Conflicts’ rules in modules.
, --keep-system-libs
Keep CFLAGS or linker flag fragments that would be filtered due to being included by default in the compiler.
, --libs-only-L, --libs-only-l, --libs-only-other
Print all linker flags required to link against the module, or only the library path (-L) flags, or only the library (-l) flags, or only the linker flags that are neither library path nor library flags, respectively. These options imply --print-errors.
Walk the module search path in the order of descending priority. For each pc(5) file found, print one line to standard output, containing the basename of the file without the extension, the Name property, a dash (‘-’), and the Description property. This option implies --print-errors. All command line arguments are ignored.
Perform the same search as --list-all, but only print the basename of each pc(5) file without the extension, not the module name and the description. This option implies --print-errors. All command line arguments are ignored.
=file
Set the name of the output file where information about selected modules is logged, both about those selected by arguments and as dependencies. For each selected module, one line is printed, containing the basename of the pc(5) file without the extension, optionally an operator and version number describing the desired range of versions, and either the actual version number in square brackets or the string "NOT-FOUND". If this option is not provided, the name of the output file is instead taken from the PKG_CONFIG_LOG environment variable, and if that is not provided either, this kind of logging is disabled.
=version
Check the module arguments in the given order. Exit with error as soon as a module does not exist, and exit with success as soon as the version number of a module is less than or equal to the requested version number. Exit with error if the version number of each module is greater than the requested version number.
=depth
Impose a limit on the allowed depth in the dependency graph. For example, a depth of 2 restricts the resolver from acting on child dependencies of modules added to the resolver's solution. This option is overridden by the PKG_CONFIG_MAXIMUM_TRAVERSE_DEPTH environment variable and by the options --modversion, --path, --print-provides, --print-requires, --print-requires-private, --print-variables, and --variable.
For each specified module, print the version number to standard output. If the --verbose option is also specified, the name of the respective module and a colon is printed before each version number. This option implies --print-errors and --maximum-traverse-depth=1 and overrides and disables all --cflags and --libs flags.
Use MSVC syntax for --cflags, --env, and --libs output. This option is only available if the preprocessor macro PKGCONF_LITE was not defined during compilation.
Skip caching packages when they are loaded into the internal resolver. This may result in an alternate dependency graph being computed.
Ignore ‘Provides’ rules in modules when resolving dependencies.
Forbids the dependency resolver from considering 'uninstalled' modules as part of a solution.
For the first module given on the command line, let the dependency resolver find the pc(5) file describing that module, print the absolute pathname of that file to standard output, and exit immediately, ignoring most other options and all other arguments.
=variable
Sets the ‘prefix’ variable used by the ‘define-prefix’ feature.
Print some messages about fatal errors to standard error output that would otherwise be omitted. This option is implied by many other options, but not by all. It can be overridden with --silence-errors.
For each specified module, print one line to standard output containing the Name property, an equal sign (‘=’), and the Version property. If the module contains one or more Provides properties, print additional lines in dependency list format, one name per line, each name optionally followed by an operator and a version. This option implies --maximum-traverse-depth=1 and overrides and disables all --cflags and --libs flags.
For each specified module, print the Requires or Requires.private properties, respectively, in dependency list format to standard output. Both of these options imply --maximum-traverse-depth=1 and override and disable all --cflags and --libs flags.
For the first module given on the command line, print the names of all seen variables to standard output, one per line. Any subsequent arguments are silently ignored. This option implies --print-errors and --maximum-traverse-depth=1 and overrides and disables all --cflags and --libs flags.
Treats the computed dependency graph as if it were pure. This is mainly intended for use with the --static flag and has no effect if --shared is also specified.
=path
Relocates a path using the pkgconf_path_relocate API. This is mainly used by the testsuite to provide a guaranteed interface to the system's path relocation backend.
Compute a simple dependency graph that is only suitable for shared linking. This option overrides --static.
When printing error messages about modules that are not found or conflict with each other, avoid printing additional, verbose instructions explaining potential methods for solving the problem.
Do not print any error, warning, or debugging messages at all. Overrides all of --debug, --errors-to-stdout, and --print-errors. This option is overridden and disabled if the PKG_CONFIG_DEBUG_SPEW environment variable is set.
Simulates resolving a dependency graph based on the requested modules on the command line. Dumps a series of trees denoting pkgconf's resolver state. This option is only available if the preprocessor macro PKGCONF_LITE was not defined during compilation.
Print the names of the modules requested with module arguments and their dependencies to standard output. This option is only available if the preprocessor macro PKGCONF_LITE was not defined during compilation.
Compute a deeper dependency graph and use compiler/linker flags intended for static linking. This option is overridden by --shared.
Exit with a non-zero result if the dependency resolver uses an ‘uninstalled’ module as part of its solution.
package ...
Validate specific ‘.pc’ files for correctness. This option implies --print-errors and --errors-to-stdout.
=varname
For the first module given on the command line, print the value of the variable with the name varname to standard output. Any subsequent arguments are silently ignored. This option implies --maximum-traverse-depth=1 and overrides and disables all --cflags and --libs flags.
This option only has an effect if --modversion is also specified. It prints the name of the respective module and a colon before each version number.
Print the version number of the pkg-config program to standard output and exit. Most other options and all command line arguments are ignored.
=path
Prepend the directory path to the module search path, giving it priority over all other directories including those from PKG_CONFIG_PATH and PKG_CONFIG_LIBDIR.

First supplementary colon-separated list of include paths filtered out in the same way as PKG_CONFIG_SYSTEM_INCLUDE_PATH.
Third supplementary colon-separated list of include paths filtered out in the same way as PKG_CONFIG_SYSTEM_INCLUDE_PATH.
Second supplementary colon-separated list of include paths filtered out in the same way as PKG_CONFIG_SYSTEM_INCLUDE_PATH.
If set to the same value as PKG_CONFIG_SYSROOT_DIR, behave in the same way as if PKG_CONFIG_FDO_SYSROOT_RULES is set. If PKG_CONFIG_SYSROOT_DIR is not set or set to a different value, DESTDIR is ignored.
Supplementary colon-separated list of library paths filtered out in the same way as PKG_CONFIG_SYSTEM_LIBRARY_PATH.
Fourth supplementary colon-separated list of include paths filtered out in the same way as PKG_CONFIG_SYSTEM_INCLUDE_PATH.
If set, this variable has the same effect as the --keep-system-cflags option.
If set, this variable has the same effect as the --keep-system-libs option.
If set, override and disable the --silence-errors option.
If set, enables the same behaviour as the --no-uninstalled flag.
If set, this variable has the same effect as the --dont-define-prefix option.
If set, disables the path relocation feature.
If set, follow the sysroot prefixing rules that freedesktop.org pkg-config uses.
If set, ignore Conflicts rules in modules. Has the same effect as the --ignore-conflicts option.
A colon-separated list of low-priority directories where pc(5) files are looked up. The module search path is constructed by appending this list to PKG_CONFIG_PATH, which enjoys higher priority. If PKG_CONFIG_LIBDIR is not defined, the default list compiled into the pkg-config program from the PKG_DEFAULT_PATH preprocessor macro is appended instead. If PKG_CONFIG_LIBDIR is defined but empty, nothing is appended.
If set, log information about selected modules to the file with the name stored in this variable. For more details, see the --log-file command line option, which overrides this variable.
Impose a limit on the allowed depth in the dependency graph. This variable overrides the --maximum-traverse-depth option, but is overridden by the other options mentioned there.
If set, use MSVC syntax for --cflags, --env, and --libs output. This variable has the same effect as the --msvc-syntax option. If the preprocessor macro PKGCONF_LITE was defined during compilation, this variable is ignored.
A colon-separated list of high-priority directories where pc(5) files are looked up. The module search path is constructed by prepending the directory specified with --with-path, if any, and unless --env-only is specified, by appending either PKG_CONFIG_LIBDIR or the compiled-in default directories with lower priority.
If set, enables the same behaviour as the --pure flag.
If set, this variable has the same effect as the --define-prefix option.
If set, this variable defines a ‘sysroot’ directory, which will be prepended to every path variable beginning with the prefix variable in a given pc(5) file. Useful for cross compilation. The value of this environment variable is also copied into the global variable pc_sysrootdir.
Colon-separated list of include paths that are filtered out and not printed by the --cflags and --cflags-only-I options because they are considered system include paths. If not defined, the default list compiled into the pkg-config program from the SYSTEM_INCLUDEDIR preprocessor macro is used instead. This variable is a pkgconf-specific extension. Any directories listed in the environment variables CPATH, C_INCLUDE_PATH, CPLUS_INCLUDE_PATH, and OBJC_INCLUDE_PATH are also filtered out.
Colon-separated list of library paths that are filtered out and not printed by the --libs and --libs-only-L options because they are considered system library paths. If not defined, the default list compiled into the pkg-config program from the SYSTEM_LIBDIR preprocessor macro is used instead. This variable is a pkgconf-specific extension.
The value of the pc_top_builddir global variable. If this environment variable is not defined, the string "$(top_builddir)" is used as the value of pc_top_builddir.

The pkg-config utility exits 0 on success, and >0 if an error occurs.

Displaying the CFLAGS of a package:

$ pkg-config --cflags foo
-fPIC -I/usr/include/foo

pc(5), pkg.m4(7)

June 7, 2025 Debian