Using CGO with Pkg-Config And Custom Dynamic Library Locations

Earlier in the month I wrote a post about using C Dynamic Libraries in Go Programs (https://www.ardanlabs.com/blog/2013/08/using-c-dynamic-libraries-in-go-programs.html). The article built a dynamic library in C and created a Go program that used it. The program worked but only if the dynamic library was in the same folder as the program.

This constraint does not allow for the use of the go get command to download, build and install a working version of the program. I did not want to have any requirements to pre-install dependencies or run extra scripts or commands after the call to go get. The Go tool was not going to copy the dynamic library into the bin folder and therefore I would not be able to run the program once the go get command was complete. This was simply unacceptable and there had to be a way to make this work.

The solution to this problem was twofold. First, I needed to use a package configuration file to specify the compiler and linker options to CGO. Second, I needed to set an environment variable so the operating system could find the dynamic library without needing to copy it to the bin folder.

If you look, you will see that some of the standard libraries provide a package configuration (.pc) file. A special program called pkg-config is used by the build tools, such as gcc, to retrieve information from these files.