NAME
kill - send signal to a process
SYNOPSIS
#include <sys/types.h>
#include <signal.h>
int kill(pid_t pid, int 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 sigaction(2), or it may be 0, in which case error check-
ing 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.
If the process number is 0, the signal is sent to all
processes in the sender's process group.
If the process number is -1 and the user is the super-user,
the signal is broadcast universally except to init 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.
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.
Processes may send signals to themselves.
RETURN VALUE
Upon successful completion, a value of 0 is returned. Oth-
erwise, a value of -1 is returned and errno is set to indi-
cate the error.
ERRORS
Kill will fail and no signal will be sent if any of the fol-
lowing occur:
[EINVAL] Sig is not a valid signal number.
[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.
[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.
When signaling a process group, this error
was returned if any members of the group
could not be signaled.
SEE ALSO
getpid(2), getpgrp(2), sigaction(2), raise(3).