# Using the library to build applications

## On UNIX platforms

The DC-API library uses the `pkg-config` system to help the building of applications. For every backend, two `pkg-config` modules are available: `dcapi-<backend>-client` for building client applications and `dcapi-<backend>-master` for building master applications.

During compilation, the `pkg-config --cflags <module>` command gives the list of compiler directives (like include file locations) that have to be passed to the compiler whenever one of the DC-API headers is referenced in a source file.

During linking, the `pkg-config --libs <module>` command will return the list of libraries and linker options required to link the application with DC-API.

If you have built DC-API from source and have installed it at a non-standard location (i.e. not under `/usr` or `/usr/local`), you may have to set the `PKG_CONFIG_PATH` environment variable to point to the directory where the `.pc` files are located in order to `pkg-config` to find them.