KILL(2)KILL(2)NAMEkill - send signal to a process
SYNOPSIS
#include <sys/types.h>
#include <signal.h>
int kill(pid_t pid, int sig);
DESCRIPTION
The kill function sends the signal sig to a process, specified by the
process number pid. Its argument 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.
For a process to have permission to send a signal to a process
designated by pid, the real or effective user ID of the sending process
must match the real or saved set-user-ID of the receiving process,
unless the sending process has superuser privileges. The only
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. If the process number is -1 and the user is not
the super-user, the signal is broadcast universally to all processes
with the same uid as the user except the process sending the signal.
No error is returned if any process could be signaled.
For compatibility with System V, if the process number is negative but
not -1, the signal is sent to all processes whose process group ID is
equal to the absolute value of the process number. This is a variant
of killpg(2).
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
The kill function will fail and no signal will be sent if any of the
following occur:
[EINVAL] sig is not a valid signal number.
[EPERM] The process does not have permission to send the
signal to any receiving process. [ESRCH] No
process can be found corresponding to that
specified by pid.
[ESRCH] The process id was given as 0 but the sending
process does not have a process group.
SEE ALSOgetpid(2), getpgrp(2), killpg(2), sigvec(2)
August 1, 1992 KILL(2)
