.\"	$NetBSD: setpgid.2,v 1.8 1995/02/27 12:36:55 cgd Exp $
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.\"     @(#)setpgid.2	8.1 (Berkeley) 6/4/93
.\"
.Dd June 4, 1993
.Dt SETPGID 2
.Os BSD 4
.Sh NAME
.Nm setpgid ,
.Nm setpgrp
.Nd set process group
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft int
.Fo setpgid
.Fa "pid_t pid"
.Fa "pid_t pgid"
.Fc
.Ft pid_t
.Fo setpgrp
.Fa void
.Fc
.Sh DESCRIPTION
.Fn setpgid
sets the process group of the specified process
.Ar pid
to the specified
.Ar pgid .
If
.Ar pid
is zero, then the call applies to the current process.
.Pp
If the invoker is not the super-user, then the affected process
must have the same effective user-id as the invoker or be a descendant
of the invoking process.
.Pp
.Sh RETURN VALUES
.Fn setpgid
returns 0 when the operation was successful.
If the request failed, -1 is returned and the global variable
.Va errno
indicates the reason.
.Sh ERRORS
.Fn setpgid
will fail and the process group will not be altered if:
.Bl -tag -width Er
.\" ===========
.It Bq Er EACCES
The value of the
.Fa pid
argument matches the process ID of a child process of the calling process, 
and the child process has successfully executed one of the exec functions.
.\" ===========
.It Bq Er EINVAL
The value of the
.Fa pgid
argument is less than 0
or is not a value supported by the implementation.
.\" ===========
.It Bq Er EPERM
The process indicated by the
.Fa pid
argument is a session leader.
.\" ===========
.It Bq Er EPERM
The effective user ID of the requested process is different
from that of the caller and the process is not a descendant
of the calling process.
.\" ===========
.It Bq Er EPERM
The value of the
.Fa pgid argument
is valid, but does not match the process ID
of the process indicated by the
.Fa pid
argument and there is no process with a process group ID
that matches the value of the
.Fa pgid
argument in the same session as the calling process.
.\" ===========
.It Bq Er ESRCH
The value of the 
.Fa pid 
argument does not match the process ID of the calling process or of a 
child process of the calling process.
.El
.Sh LEGACY SYNOPSIS
.Fd #include <unistd.h>
.Pp
.Ft int
.br
.Fo setpgrp
.Fa "pid_t pid"
.Fa "pid_t pgid"
.Fc ;
.Pp
The legacy
.Fn setpgrp
function is a clone of the
.Fn setpgid
function, retained for calling convention compatibility
with historical versions of
.Bx .
.Sh COMPATIBILITY
Use of the legacy version of the
.Fn setpgrp
call will cause compiler diagnostics.
Use
.Fn setpgid
instead.
.Pp
Use of private (and conflicting) prototypes for
.Fn setpgrp
will cause compiler diagnostics.
Delete the private prototypes and include
.In unistd.h .
.Sh SEE ALSO
.Xr getpgrp 2 ,
.Xr compat 5
.Sh STANDARDS
The
.Fn setpgid
function conforms to 
.St -p1003.1-88 .