KILL(2)                              BSD                               KILL(2)



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 can always be sent to any descendant of the
     current process.

     In some implementations, 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).  Domain/OS BSD, however, has no process number 0.

     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 can send signals to themselves.

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.

     [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), killpg(2), sigvec(2)

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