To install or compile GIMP filters, plugins, or extensions on Linux, follow these steps:
Make sure that you have the necessary dependencies installed on your system. This may include libraries such as GTK+ and GLib, as well as development tools such as GCC and Make.
Download the source code for the GIMP filter, plugin, or extension you want to install. This may be available as a tarball or ZIP file from the project's website, or you may need to clone the project's Git repository.
Extract the source code from the tarball or ZIP file, or navigate to the project's directory if you cloned the Git repository.
Follow the instructions provided with the source code to build and install the filter, plugin, or extension. This may involve running the ./configure script followed by make and make install, or it may have different build instructions.
Once the build process is complete, the filter, plugin, or extension should be installed and available for use in GIMP. You may need to restart GIMP or enable the filter, plugin, or extension in the GIMP preferences for it to become active.
That's it! You should now be able to use the GIMP filter, plugin, or extension on your Linux system.