PC(5)

NAME
file.pc - pkg-config file format

DESCRIPTION
pkg-config files provide a useful mechanism for storing various information about libraries and packages on a given system. Information stored by .pc files include compiler and linker flags necessary to use a given library, as well as any other relevant metadata.

These .pc files are processed by a utility called pkg-config, of which pkgconf is an implementation.

  FILE SYNTAX
The .pc file follows a format inspired by RFC822. Comments are prefixed by a pound sign, hash sign or octothorpe (#), and variable assignment is similar to POSIX shell. Properties are defined using RFC822-style stanzas.

  VARIABLES
Variable definitions start with an alphanumeric string, followed by an equal sign, and then the value the variable should contain.

Variable references are always written as "${variable}". It is possible to escape literal "${" as "$${".

  PROPERTIES
Properties are set using RFC822-style stanzas which consist of a keyword, followed by a colon (:) and then the value the property should be set to. Variable substitution is always performed regardless of property type.

There are three types of property:

Literal
    The property will be set to the text of the value.

Dependency List
    The property will be set to a list of dependencies parsed from the text. Dependency lists are defined by this ABNF syntax:

        package-list = *WSP *( package-spec *( package-sep ) )
        package-sep  = WSP / ","
        package-spec = package-key [ ver-op package-version ]
        ver-op       = "<" / "<=" / "=" / "!=" / ">=" / ">"

Fragment List
    The property will be set to a list of fragments parsed from the text. The input text must be in a format that is suitable for passing to a POSIX shell without any shell expansions after variable substitution has been done.

    The text is tokenised using POSIX shell word-splitting rules: unquoted whitespace separates fragments, single and double quotes group text, and a backslash escapes the following character. A quote that is not itself escaped is consumed as a quoting delimiter and does not appear in the resulting fragment. To include a shell metacharacter — such as a quote, whitespace, a bracket, a brace, or a glob character — literally in a fragment, escape it with a backslash so that it survives tokenisation.

    For example, to make the toolchain receive the argument

        -sFUNCS=["fnA","fnB"]

    escape the double quotes so they are not consumed as quoting:

        Libs: -sFUNCS=[\"fnA\",\"fnB\"]

    On output, such metacharacters are re-escaped so that the original fragment is recovered when the consumer tokenises the output using the same shell word-splitting rules; see the note on output escaping in pkgconf(1).

  PROPERTY KEYWORDS

Name
    The displayed name of the package. (mandatory; literal)

Version
    The version of the package. (mandatory; literal)

Description
    A description of the package. (mandatory; literal)

URL A URL to a webpage for the package. This is used to recommend where newer versions of the package can be acquired. (mandatory; literal)

Cflags
    Required compiler flags. These flags are always used, regardless of whether static compilation is requested. (optional; fragment list)

Cflags.private
    Required compiler flags for static compilation only. (optional; fragment list; pkgconf extension; introduced in pkgconf 0.9.3)

Cflags.shared
    Required compiler flags for shared compilation only. (optional; fragment list; pkgconf extension; introduced in pkgconf 3.0.0)

Copyright
    A copyright attestation statement. (optional; literal; pkgconf extension; introduced in pkgconf 1.9.3)

Libs
    Required linking flags for this package. Libraries this package depends on for linking against it, which are not described as dependencies should be specified here. (optional; fragment list)

Libs.private
    Required linking flags for this package that are only required when linking statically. Libraries this package depends on for linking against it statically, which are not described as dependencies should be specified here. (optional; fragment list)

Libs.shared
    Required linking flags for this package that are only required for dynamic linking. Libraries this package depends on for linking against it dynamically, which are not described as dependencies should be specified here. (optional; fragment list; pkgconf extension; introduced in pkgconf 3.0.0)

Link.ABI
    A comma-separated list of tags describing the application binary interfaces a consumer must link this package against, such as c++ or fortran. Tags are case-insensitive and are normalized to lowercase. This allows a build system to select the appropriate linker driver and runtime when a package, or one of its dependencies, is implemented in a language whose ABI differs from C. The tag set is unioned across the dependency closure in the same manner as Libs: a package's own tags and those of its public Requires always apply, while Requires.private tags apply only when private dependencies are linked. Unlike a runtime library load, ABI compatibility of the exposed interface applies equally to shared and static linking. A package with no Link.ABI property is treated as c. (optional; pkgconf extension; introduced in pkgconf 3.0.0)

License
    The asserted SPDX license tag that should be applied to the given package. One should try to determine the correct SPDX license tag for package from the SPDX License list. If a standard license name isn't available, use the LicenseRef-tag. For complex licensing details, utilize SPDX expression notation. It’s possible to assign multiple license tags in pc-file, which are then merged together with an 'AND' when rendering output. (optional; literal; pkgconf extension; introduced in pkgconf 1.9.0)

License.file
    An absolute filesystem path to the installed file containing the full license text for this package. The path must refer to the license file as installed on the system, so that it corresponds to the exact version and configuration described by this .pc file; pkgconf variable references such as ${prefix} or ${datadir}, which expand to absolute paths, may be used. Relative paths are not supported. This must not be a URL: use Source to reference an upstream location. (optional; literal; pkgconf extension; introduced in pkgconf 3.0.0)

Maintainer
    The preferred contact for the maintainer. This should be in the format of a name followed by an e-mail address or website. (optional; literal; pkgconf extension; introduced in pkgconf 1.9.3)

Source
    The asserted SPDX downloadLocation tag that should be applied to the given package. Source should be URI contain tarball with exact version or Repository that contains tag with version same as mentioned in version tag. It can be also be URI with hash that is exact release point of the source. (optional; literal; pkgconf extension; introduced in pkgconf 3.0.0)

Requires
    Required dependencies that must be met for the package to be usable. All dependencies must be satisfied or the pkg-config implementation must not use the package. (optional; dependency list)

Requires.internal
    Required dependencies that must be met for the package to be usable for static linking. The main differences verses Requires.private are that CFLAGS will not be included and the solver will not consider the dependency when solving for CFLAGS only. (optional; dependency list; pkgconf extension; introduced in pkgconf 1.5.0)

Requires.private
    Required dependencies that must be met for the package to be usable for header inclusion and static linking. All dependencies must be satisfied or the pkg-config implementation must not use the package for header inclusion and static linking. (optional; dependency list)

Requires.shared
    Required dependencies that are only traversed when not in static mode. This allows a package to express dependencies that are only relevant when it is used as a shared library. (optional; dependency list; pkgconf extension; introduced in pkgconf 3.0.0)

Conflicts
    Dependencies that must not be met for the package to be usable. If any package in the proposed dependency solution match any dependency in the Conflicts list, the package being considered is not usable. (optional; dependency list)

Provides
    Dependencies that may be provided by an alternate package. If a package cannot be found, the entire package collection is scanned for providers which can match the requested dependency. (optional; dependency list; pkgconf extension; introduced in pkgconf 1.1.0)

  EXTENSIONS
Features that have been marked as a pkgconf extension are only guaranteed to work with the pkgconf implementation of pkg-config. Other implementations may or may not support the extensions.

Accordingly, it is suggested that .pc files which absolutely depend on these extensions declare a requirement on the pkgconf virtual.

In addition it should be noted that the pkgconf virtual is versioned, and thus files which absolutely depend on these extensions can declare a requirement on the specific pkgconf version which introduced the extension.

As an example:

    Requires: pkgconf >= 3.0.0
    Libs.shared: ...

EXAMPLES
An example .pc file:

    # This is a comment
    prefix=/home/kaniini/pkg   # this defines a variable
    exec_prefix=${prefix}      # defining another variable with a substitution
    libdir=${exec_prefix}/lib
    includedir=${prefix}/include
    Name: libfoo                                  # human-readable name
    Description: an example library called libfoo # human-readable description
    Copyright: Copyright (c) 2022 pkgconf project authors
    License: Apache-2.0
    Maintainer: the pkgconf project <http://www.pkgconf.org>
    Version: 1.0
    URL: http://www.pkgconf.org
    Requires: libbar > 2.0.0
    Conflicts: libbaz <= 3.0.0
    Libs: -L${libdir} -lfoo
    Libs.private: -lm
    Cflags: -I${includedir}/libfoo

SEE ALSO
pkgconf(1), pkg.m4(7)