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.\"     from: @(#)setregid.2	6.4 (Berkeley) 3/10/91
.\"	$Id: setregid.3,v 1.1 1995/10/18 08:41:46 deraadt Exp $
.\"
.Dd March 10, 1991
.Dt SETREGID 3
.Os BSD 4.2
.Sh NAME
.Nm setregid
.Nd set real and effective group ID's
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft int
.Fn setregid "int rgid" "int egid"
.Sh DESCRIPTION
The real and effective group ID's of the current process
are set to the arguments.
Unprivileged users may change the real group
ID to the effective group ID and vice-versa; only the super-user may
make other changes.
.Pp
Supplying a value of -1 for either the real or effective
group ID forces the system to substitute the current
ID in place of the -1 parameter.
.Pp
The 
.Fn setregid
function was intended to allow swapping the real and
effective group IDs in set-group-ID programs to temporarily relinquish
the set-group-ID value.  This function did not work correctly, and its
purpose is now better served by the use of the
.Fn setegid
function (see
.Xr setuid 2 ).
.Pp
When setting the real and effective group IDs to the same value, the
standard
.Fn setgid
function is preferred.
.Sh RETURN VALUES
Upon successful completion, a value of 0 is returned.  Otherwise,
a value of -1 is returned and
.Va errno
is set to indicate the error.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er EPERM
The current process is not the super-user and a change
other than changing the effective group-id to the real group-id
was specified.
.El
.Sh SEE ALSO
.Xr getgid 2 ,
.Xr setegid 2 ,
.Xr setgid 2 ,
.Xr setuid 2
.Sh HISTORY
The
.Fn setregid
function call appeared in
.Bx 4.2
and was dropped in
.Bx 4.4 .