4.4BSD/usr/share/man/cat2/kill.0

KILL(2)                     BSD Programmer's Manual                    KILL(2)

NNAAMMEE
     kkiillll - send signal to a process

SSYYNNOOPPSSIISS
     ##iinncclluuddee <<ssiiggnnaall..hh>>

     _i_n_t
     kkiillll(_p_i_d___t _p_i_d, _i_n_t _s_i_g);

DDEESSCCRRIIPPTTIIOONN
     The kkiillll() function sends the signal given by _s_i_g to _p_i_d, a process or a
     group of processes.  _S_i_g may be one of the signals specified in sigac-
     tion(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 _p_i_d.

     For a process to have permission to send a signal to a process designated
     by _p_i_d, the real or effective user ID of the receving process must match
     that of the sending process or the user must have appropriate privileges
     (such as given by a set-user-ID program or the user is the super-user).
     A single exception is the signal SIGCONT, which may always be sent to any
     descendant of the current process.

     If _p_i_d is greater than zero:
             _S_i_g is sent to the process whose ID is equal to _p_i_d_.

     If _p_i_d is zero:
             _S_i_g is sent to all processes whose group ID is equal to the pro-
             cess group ID of the sender, and for which the process has per-
             mission; this is a variant of killpg(2).

     If _p_i_d is -1:
             If the user has super user privileges, the signal is sent to all
             processes excluding system processes and the process sending the
             signal.  If the user is not the super user, the signal is sent to
             all processes with the same uid as the user excluding 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).

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

EERRRROORRSS
     KKiillll() will fail and no signal will be sent if:

     [EINVAL]  _S_i_g is not a valid signal number.

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

     [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 us-
               er id does not match the effective user-id of the receiving
               process.  When signaling a process group, this error is re-
               turned if any members of the group could not be signaled.

SSEEEE AALLSSOO
     getpid(2),  getpgrp(2),  killpg(2),  sigaction(2)

SSTTAANNDDAARRDDSS
     The kkiillll() function is expected to conform to IEEE Std 1003.1-1988
     (``POSIX'').

4th Berkeley Distribution        June 4, 1993                                2