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kc3-lang/pkgconf/README.md
William Pitcock
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# pkgconf [](https://travis-ci.org/pkgconf/pkgconf) pkgconf provides compiler and linker configuration for development frameworks. ## general summary pkgconf is a program which helps to configure compiler and linker flags for development frameworks. It is similar to pkg-config, but was written from scratch in the summer of 2011 to replace pkg-config, which for a while needed itself to build itself (they have since included a 'stripped down copy of glib 2.0') Since then we have worked on improving pkg-config for embedded use. If you're wondering what pkg-config is useful for, you might find the tutorial/guide docs for [legacy pkg-config][pcdocs] useful. [pcdocs]: http://people.freedesktop.org/~dbn/pkg-config-guide.html ## usage 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 enviornment variable on the bourne shell and clones (i.e. bash), you can run: $ export PKG_CONFIG=/usr/bin/pkgconf ## technical design (why pkgconf is better for distros) 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. pkg-config, on the other hand builds 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. pkgconf also does not bundle any third-party libraries or depend on any third-party libraries, making it a great tool for embedded systems and distributions with security concerns. ## other differences verses pkg-config 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 Beyond that, we do not provide bug-level compatibility with pkg-config. What that means is, if you feel that there is a legitimate regression verses pkg-config, do let us know, but also make sure that the .pc files are valid and follow the rules of the [pkg-config tutortial][fd-tut], as most likely fixing them to follow the specified rules will solve the problem. ## compiling 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 <http://rabbit.dereferenced.org/~nenolod/distfiles/>. ## reporting bugs See <https://github.com/pkgconf/pkgconf/issues>. Also you can contact us at `#pkgconf` at `irc.freenode.net`.