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kc3-lang/pkgconf/README.md
William Pitcock
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# pkgconf [](https://travis-ci.org/pkgconf/pkgconf) [](http://pkgconf.readthedocs.io/en/latest/?badge=latest) `pkgconf` is a program which helps to configure compiler and linker flags for development frameworks. It is similar to pkg-config from freedesktop.org. `libpkgconf` is a library which provides access to most of `pkgconf`'s functionality, to allow other tooling such as compilers and IDEs to discover and use frameworks configured by pkgconf. ## using `pkgconf` with autotools Implementations of pkg-config, such as pkgconf, are typically used with the PKG_CHECK_MODULES autoconf macro. As far as we know, pkgconf is compatible with all known variations of this macro. pkgconf detects at runtime whether or not it was started as 'pkg-config', and if so, attempts to set program options such that its behaviour is similar. In terms of the autoconf macro, it is possible to specify the PKG_CONFIG environment variable, so that you can test pkgconf without overwriting your pkg-config binary. Some other build systems may also respect the PKG_CONFIG environment variable. To set the environment variable on the bourne shell and clones (i.e. bash), you can run: $ export PKG_CONFIG=/usr/bin/pkgconf ## comparison of `pkgconf` and `pkg-config` dependency resolvers pkgconf builds an acyclic directed dependency graph. This allows for the user to more conservatively link their binaries -- which may be helpful in some environments, such as when prelink(1) is being used. As a result of building a directed dependency graph designed for the specific problem domain provided by the user, more accurate dependencies can be determined. Current release versions of pkg-config, on the other hand, build a database of all known pkg-config files on the system before attempting to resolve dependencies, which is a considerably slower and less efficient design. Efforts have been made recently to improve this behaviour. As of the 1.1 series, pkgconf also fully implements support for `Provides` rules, while pkg-config does not. pkg-config only provides the `--print-provides` functionality as a stub. There are other intentional implementation differences in pkgconf's dependency resolver verses pkg-config's dependency resolver in terms of completeness and correctness, such as, for example, how `Conflicts` rules are processed. ## linker flags optimization As previously mentioned, pkgconf makes optimizations to the linker flags in both the case of static and shared linking in order to avoid overlinking binaries and also simplifies the `CFLAGS` and `LIBS` output of the pkgconf tool for improved readability. This functionality depends on the pkg-config module properly declaring it's dependency tree instead of using `Libs` and `Cflags` fields to directly link against other modules which have pkg-config metadata files installed. Doing so is discouraged by the [freedesktop tutorial][fd-tut] anyway. [fd-tut]: http://people.freedesktop.org/~dbn/pkg-config-guide.html ## compatibility with pkg-config We do not provide bug-level compatibility with pkg-config. What that means is, if you feel that there is a legitimate regression versus pkg-config, do let us know, but also make sure that the .pc files are valid and follow the rules of the [pkg-config tutorial][fd-tut], as most likely fixing them to follow the specified rules will solve the problem. ## compiling `pkgconf` and `libpkgconf` pkgconf is basically compiled the same way any other autotools-based project is compiled: $ ./configure $ make $ sudo make install If you are installing pkgconf into a custom prefix, such as `/opt/pkgconf`, you will likely want to define the default system includedir and libdir for your toolchain. To do this, use the `--with-system-includedir` and `--with-system-libdir` configure flags like so: $ ./configure \ --prefix=/opt/pkgconf \ --with-system-libdir=/lib:/usr/lib \ --with-system-includedir=/usr/include $ make $ sudo make install If you want pkgconf to be used when you invoke `pkg-config`, you should install a symlink for this. We do not do this for you, as we believe it is better for vendors to make this determination themselves. $ ln -sf /usr/bin/pkgconf /usr/bin/pkg-config ## release tarballs Release tarballs are available at <https://distfiles.dereferenced.org/pkgconf/>. Please do not use the github tarballs as they are not pristine (instead generated by github everytime a download occurs). ## reporting bugs See <https://github.com/pkgconf/pkgconf/issues>. Also you can contact us at `#pkgconf` at `irc.freenode.net`.