1.\"	$OpenBSD: initgroups.3,v 1.16 2015/02/05 02:33:09 schwarze Exp $
2.\"
3.\" Copyright (c) 1983, 1991, 1993
4.\"	The Regents of the University of California.  All rights reserved.
5.\"
6.\" Redistribution and use in source and binary forms, with or without
7.\" modification, are permitted provided that the following conditions
8.\" are met:
9.\" 1. Redistributions of source code must retain the above copyright
10.\"    notice, this list of conditions and the following disclaimer.
11.\" 2. Redistributions in binary form must reproduce the above copyright
12.\"    notice, this list of conditions and the following disclaimer in the
13.\"    documentation and/or other materials provided with the distribution.
14.\" 3. Neither the name of the University nor the names of its contributors
15.\"    may be used to endorse or promote products derived from this software
16.\"    without specific prior written permission.
17.\"
18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28.\" SUCH DAMAGE.
29.\"
30.Dd $Mdocdate: February 5 2015 $
31.Dt INITGROUPS 3
32.Os
33.Sh NAME
34.Nm initgroups
35.Nd initialize supplementary group IDs
36.Sh SYNOPSIS
37.In unistd.h
38.Ft int
39.Fn initgroups "const char *name" "gid_t basegid"
40.Sh DESCRIPTION
41The
42.Fn initgroups
43function uses the
44.Xr getgrouplist 3
45function to calculate the supplementary group IDs for the user specified in
46.Fa name .
47This group list is then set up for the current process using
48.Xr setgroups 2 .
49The
50.Fa basegid
51is automatically included in the group list.
52Typically this value is given as the group number from the password file.
53.Pp
54If the groups database lists more than
55.Dv NGROUPS_MAX
56groups for
57.Fa name
58(including one for
59.Fa basegid ) ,
60the later groups are ignored.
61.Sh RETURN VALUES
62The
63.Fn initgroups
64function returns \-1 if it was not invoked by the superuser.
65.Sh SEE ALSO
66.Xr setgroups 2 ,
67.Xr getgrouplist 3
68.Sh HISTORY
69The
70.Fn initgroups
71function appeared in
72.Bx 4.2 .
73.Sh BUGS
74The
75.Xr getgrouplist 3
76function called by
77.Fn initgroups
78uses the routines based on
79.Xr getgrent 3 .
80If the invoking program uses any of these routines, the group structure
81will be overwritten in the call to
82.Fn initgroups .
83