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KILL(2)			  FreeBSD System Calls Manual		       KILL(2)

     kill -- send signal to a process

     #include <signal.h>

     kill(pid_t	pid, int sig);

     The kill()	function sends the signal given	by sig to pid, a process or a
     group of processes.  Sig may be one of the	signals	specified in
     sigaction(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 receiving 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	pid is greater than zero:
	     Sig is sent to the	process	whose ID is equal to pid.

     If	pid is zero:
	     Sig is sent to all	processes whose	group ID is equal to the
	     process group ID of the sender, and for which the process has
	     permission; this is a variant of killpg(2).

     If	pid 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

     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

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

     Kill() will fail and no signal will be sent if:

     [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 is
	       returned	if any members of the group could not be signaled.

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

     The kill()	function call is expected to conform to	ISO/IEC	9945-1:1990

     A kill() function call appeared in	Version	7 AT&T UNIX.

4th Berkeley Distribution	April 19, 1994	     4th Berkeley Distribution


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