1.\" Copyright (c) 1983, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)getgroups.2 8.2 (Berkeley) 4/16/94 29.\" $FreeBSD$ 30.\" 31.Dd January 21, 2011 32.Dt GETGROUPS 2 33.Os 34.Sh NAME 35.Nm getgroups 36.Nd get group access list 37.Sh LIBRARY 38.Lb libc 39.Sh SYNOPSIS 40.In unistd.h 41.Ft int 42.Fn getgroups "int gidsetlen" "gid_t *gidset" 43.Sh DESCRIPTION 44The 45.Fn getgroups 46system call 47gets the current group access list of the user process 48and stores it in the array 49.Fa gidset . 50The 51.Fa gidsetlen 52argument 53indicates the number of entries that may be placed in 54.Fa gidset . 55The 56.Fn getgroups 57system call 58returns the actual number of groups returned in 59.Fa gidset . 60At least one and as many as {NGROUPS_MAX}+1 values may be returned. 61If 62.Fa gidsetlen 63is zero, 64.Fn getgroups 65returns the number of supplementary group IDs associated with 66the calling process without modifying the array pointed to by 67.Fa gidset . 68.Pp 69The value of 70.Dv {NGROUPS_MAX} 71should be obtained using 72.Xr sysconf 3 73to avoid hard-coding it into the executable. 74.Sh RETURN VALUES 75A successful call returns the number of groups in the group set. 76A value of -1 indicates that an error occurred, and the error 77code is stored in the global variable 78.Va errno . 79.Sh ERRORS 80The possible errors for 81.Fn getgroups 82are: 83.Bl -tag -width Er 84.It Bq Er EINVAL 85The argument 86.Fa gidsetlen 87is smaller than the number of groups in the group set. 88.It Bq Er EFAULT 89The argument 90.Fa gidset 91specifies 92an invalid address. 93.El 94.Sh SEE ALSO 95.Xr setgroups 2 , 96.Xr initgroups 3 , 97.Xr sysconf 3 98.Sh STANDARDS 99The 100.Fn getgroups 101system call conforms to 102.St -p1003.1-2008 . 103.Sh HISTORY 104The 105.Fn getgroups 106system call appeared in 107.Bx 4.2 . 108