KILL(2) — SYSTEM CALLS

NAME

kill − send signal to a process

SYNOPSIS

kill(pid, sig)
int pid, sig;

DESCRIPTION

Kill sends the signal sig to a process, specified by the process number pid. Sig may be one of the signals specified in sigvec(2), or it may be 0, in which case error checking is performed but no signal is actually sent. This can be used to check the validity of pid.

The sending and receiving processes must have the same effective user ID, otherwise this call is restricted to the super-user. A single exception is the signal SIGCONT, which may always be sent to any descendant of the current process.

If the process number is 0, the signal is sent to all processes in the sender’s process group; this is a variant of killpg(2).

If the process number is −1 and the user is the super-user, the signal is broadcast universally except to system processes and the process sending the signal.

Processes may send signals to themselves.

RETURN VALUE

Upon successful completion, a value of 0 is returned. Otherwise, a value of −1 is returned and errno is set to indicate the error.

ERRORS

Kill will fail and no signal will be sent if any of the following occur:

EINVAL Sig is not a valid signal number.

ESRCH No process can be found corresponding to that specified by pid.

EPERM The sending process is not the super-user and its effective user id does not match the effective user-id of the receiving process.

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