Also useful for operating one process which might provide access to certain files, to other processes. You can further restrict it using the fact that you can

Also useful for operating one process which might provide access to certain files, to other processes. You can further restrict it using the fact that you can easily verify the PID/UID/GID on the other end of the UNIX socket. (https://man7.org/linux/man-pages/man7/unix.7.html https://man7.org/linux/man-pages/man7/unix.7.html see SO_PEERCRED) You can also manually send your PID/UID/GID (which allows you to specify any of your real-, effective-, or saved set- *ID; or if you're root anything).