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.\"	$OpenBSD: killpg.3,v 1.9 2003/06/02 20:18:33 millert Exp $
.\"
.Dd March 10, 1991
.Dt KILLPG 3
.Os
.Sh NAME
.Nm killpg
.Nd send signal to a process group
.Sh SYNOPSIS
.Fd #include <signal.h>
.Ft int
.Fn killpg "pid_t pgrp" "int sig"
.Sh DESCRIPTION
.Fn killpg
sends the signal
.Fa sig
to the process group
.Fa pgrp .
See
.Xr sigaction 2
for a list of signals.
If
.Fa pgrp
is 0,
.Fn killpg
sends the signal to the sending process's process group.
.Pp
The sending process and members of the process group must
have the same effective user ID, or
the sender must be the superuser.
As a single special case the continue signal SIGCONT may be sent
to any process that is a descendant of the current process.
.Sh RETURN VALUES
Upon successful completion, a value of 0 is returned.
Otherwise, a value of \-1 is returned and the global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn killpg
will fail and no signal will be sent if:
.Bl -tag -width Er
.It Bq Er EINVAL
.Fa sig
is not a valid signal number.
.It Bq Er ESRCH
No process can be found in the process group specified by
.Fa pgrp .
.It Bq Er ESRCH
The process group was given as 0
but the sending process does not have a process group.
.It Bq Er EPERM
The sending process is not the superuser and one or more
of the target processes has an effective user ID different from that
of the sending process.
.El
.Sh SEE ALSO
.Xr getpgrp 2 ,
.Xr kill 2 ,
.Xr sigaction 2
.Sh HISTORY
The
.Fn killpg
function call appeared in
.Bx 4.0 .