Question - What are the possible return values of kill() system call?
Answer -
Kill() system call is used to send signals to any processes.
This method returns the following return values:
Returns 0: It implies that the process exists with the given pid and the system allows sending signals to it.
Return -1 and errno==ESRCH: It implies that there is no existence of the process with specified pid. There may also exist some security reasons which is denying the existence of the pid.
Return -1 and errno==EPERM: It implies that there is no permit available for the process to be killed. The error also detects whether the process is present or not.
EINVAl: it implies an invalid signal.