Is it possible to send a signal to process that belongs to different user?
linux, posix, signals
Solution
Quote from kill(2):
For a process to have permission to send a signal it must either be privileged
(under Linux: have the CAP_KILL capability), or the real or effective user ID
of the sending process must equal the real or saved set-user-ID of the target
process. In the case of SIGCONT it suffices when the sending and receiving
processes belong to the same session.
You can find capabilities(7) and setcap(8) useful.
Problem
I need to send a signal to different process for some real-time communication, however the process belongs to different user. For example ``` PID user group 1234 foo foobar 4321 bar foobar ``` I want process 1234 and 4321 to be able to send signals to each other? If I was using sockets or pipes I could set their mask to `rw-rw-r--` and communication would work. However I need to do the communication using signals (ordinary or real time, not important). Is there a way to do it?