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Asked: 2024-09-25T02:38:49+05:30 In:

How can I set the PKG_CONFIG_PATH environment variable in Ubuntu to specify additional directories for pkg-config to search for package configuration files?

I’ve been diving into some development stuff on my Ubuntu machine, and I just hit a bit of a wall with pkg-config. I know it’s supposed to help manage compiler and linker flags for libraries, but I can’t figure out how to set the PKG_CONFIG_PATH environment variable to point to directories where my custom library files are located.

I mean, I’ve installed some libraries in non-standard locations, and it feels like pkg-config has no clue where to look for the configuration files. I’ve read a bunch of tutorials and forum threads, but the info seems to be all over the place. Some suggest modifying the .bashrc file, while others mention running a command in the terminal, and I’m just a bit lost on which is the best approach.

What I want is something straightforward—like, if I have a directory at `/home/user/mylibs/lib/pkgconfig` where my `.pc` files are hanging out, how exactly do I tell pkg-config about this? Do I just need to export the PKG_CONFIG_PATH variable? And if so, do I have to do this every time I start a new terminal session, or is there a way to make this permanent?

Also, could you explain the difference between adding it temporarily in a session versus making it a permanent change? I feel like this knowledge would really help me when pulling in libraries for different projects because I don’t want to have to remember to set this again and again.

And, just so I’m clear, after I set it, what commands should I run to verify that pkg-config is picking up the new path? What’s the best way to double-check if everything is working smoothly?

I’m hoping someone who’s been through this can share some experiences and maybe provide a step-by-step guide. Thanks!

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    2 Answers



    1. Setting PKG_CONFIG_PATH on Ubuntu

      How to Set PKG_CONFIG_PATH for Pkg-config on Ubuntu

      If you’re trying to get pkg-config to recognize your custom libraries, it’s pretty straightforward! You need to use the PKG_CONFIG_PATH environment variable to tell pkg-config where to look for your `.pc` files.

      Temporarily Setting PKG_CONFIG_PATH

      To set it temporarily (which lasts until you close the terminal), just run this command in your terminal:

      export PKG_CONFIG_PATH=/home/user/mylibs/lib/pkgconfig

      After that, pkg-config should be able to find your libraries when you use it in the same terminal session!

      Making PKG_CONFIG_PATH Permanent

      If you want to make this change permanent (so you don’t have to set it every time), you can add the export command to your .bashrc file. Here’s how:

      1. Open the terminal.
      2. Type nano ~/.bashrc to open your bash configuration file in the nano text editor.
      3. Scroll to the bottom of the file and add this line:
        4. export PKG_CONFIG_PATH=/home/user/mylibs/lib/pkgconfig
      4. Press Ctrl + O to save, then Ctrl + X to exit.
      5. To apply the changes, run source ~/.bashrc in the terminal.

      Temporary vs Permanent Changes

      The difference between temporary and permanent changes is pretty simple:

      • Temporary: Set for the current terminal session only. You have to set it again in a new terminal.
      • Permanent: It gets set every time you open a new terminal, no need to remember to do it each time.

      Verifying Your Setup

      To check if pkg-config is now aware of your new path, run:

      pkg-config --variable=pc_path pkg-config

      This command should list the pathways known to pkg-config, including your custom directory. You can also test if pkg-config can find a specific library:

      pkg-config --cflags --libs your_library_name

      Replace your_library_name with the name of the library you’re trying to use. If it returns flags, you’re all set!

      That’s pretty much it! You should now be able to use pkg-config with your custom libraries without any hassle.


    2. To set the PKG_CONFIG_PATH environment variable in Ubuntu, you’re correct that you can either temporarily modify it for the current terminal session or make a permanent change. For a temporary session change, you can run the following command in your terminal: export PKG_CONFIG_PATH=/home/user/mylibs/lib/pkgconfig. This will set the variable for that session only, meaning it will be reset to its default value once you close the terminal window or start a new session. If you want to make this change permanent, you’ll need to add the export command to your .bashrc file. You can do this by opening the file in a text editor (e.g., nano ~/.bashrc) and adding the line export PKG_CONFIG_PATH=/home/user/mylibs/lib/pkgconfig:$PKG_CONFIG_PATH. This way, every time you open a new terminal, the PKG_CONFIG_PATH will be set automatically, allowing pkg-config to find your custom library files without any extra steps.

      To verify that pkg-config is recognizing the new path after you’ve set it, you can use the command pkg-config --variable=pkglibdir or pkg-config --list-all. Replace <library-name> with the actual library you’re trying to check. This will let you see if pkg-config is able to find and utilize the .pc files in the specified directory. If you’ve added your custom path correctly, you should see your libraries listed. If not, you might need to double-check the path you’ve set in PKG_CONFIG_PATH or the contents of your library directory to ensure the .pc files are present and formatted correctly. This way, you can smoothly manage and integrate libraries into your development projects without constantly reconfiguring your environment.

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