kill(2)                                                   kill(2)



     NAME
          kill - send a signal to a process or a group of processes

     SYNOPSIS
          int kill(pid, sig)
          int pid, sig;

     DESCRIPTION
          kill sends a signal to a process or a group of processes.
          The process or group of processes to which the signal is
          sent is specified by pid.  The signal that is to be sent is
          specified by sig and is either one from the list given in
          signal(3), or 0.  If sig is 0 (the null signal), error
          checking is performed but no signal is actually sent.  This
          can be used to check the validity of pid.

          The real or effective user ID of the sending process must
          match the real or saved effective user ID of the receiving
          process, unless the effective user ID of the sending process
          is the superuser.

          The processes with a process ID of 0 and a process ID of 1
          are special processes (see intro(2)) and will be referred to
          later as proc0 and proc1 respectively.

          If pid is greater than zero, sig will be sent to the process
          whose process ID is equal to pid; pid may equal 1.

          If pid is 0, sig will be sent to all processes excluding
          proc0 and proc1 whose process group ID is equal to the pro-
          cess group ID of the sender.

          If pid is -1 and the effective user ID of the sender is not
          the superuser, sig will be sent to all processes excluding
          proc0 and proc1 and to the sender whose real user ID is
          equal to the saved effective user ID of the sender.

          If pid is -1 and the effective user ID of the sender is the
          superuser, sig will be sent to the sender and to all
          processes excluding proc0 and proc1.

          If pid is negative but not -1, sig will be sent to all
          processes whose process group ID is equal to the absolute
          value of pid.

     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.






     April, 1990                                                     1

     kill(2)                                                   kill(2)



     ERRORS
          kill will fail and no signal will be sent if one or more of
          the following is true.

          [EINVAL]       sig is not a valid signal number.

          [EINVAL]       sig is SIGKILL and pid is 1 (proc1).

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

          [EPERM]        The sending process is not sending to itself,
                         its effective user ID is not the superuser,
                         and its real or effective user ID does not
                         match the real or effective user ID of the
                         receiving process.

     SEE ALSO
          kill(1), getpid(2), setpgrp(2), sigvec(2), signal(3).




































     2                                                     April, 1990