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.\" 30.Dd January 21, 2011 31.Dt GETGROUPS 2 32.Os 33.Sh NAME 34.Nm getgroups 35.Nd get group access list 36.Sh LIBRARY 37.Lb libc 38.Sh SYNOPSIS 39.In unistd.h 40.Ft int 41.Fn getgroups "int gidsetlen" "gid_t *gidset" 42.Sh DESCRIPTION 43The 44.Fn getgroups 45system call 46gets the current group access list of the user process 47and stores it in the array 48.Fa gidset . 49The 50.Fa gidsetlen 51argument 52indicates the number of entries that may be placed in 53.Fa gidset . 54The 55.Fn getgroups 56system call 57returns the actual number of groups returned in 58.Fa gidset . 59At least one and as many as {NGROUPS_MAX}+1 values may be returned. 60If 61.Fa gidsetlen 62is zero, 63.Fn getgroups 64returns the number of supplementary group IDs associated with 65the calling process without modifying the array pointed to by 66.Fa gidset . 67.Pp 68The value of 69.Dv {NGROUPS_MAX} 70should be obtained using 71.Xr sysconf 3 72to avoid hard-coding it into the executable. 73.Sh RETURN VALUES 74A successful call returns the number of groups in the group set. 75A value of -1 indicates that an error occurred, and the error 76code is stored in the global variable 77.Va errno . 78.Sh ERRORS 79The possible errors for 80.Fn getgroups 81are: 82.Bl -tag -width Er 83.It Bq Er EINVAL 84The argument 85.Fa gidsetlen 86is smaller than the number of groups in the group set. 87.It Bq Er EFAULT 88The argument 89.Fa gidset 90specifies 91an invalid address. 92.El 93.Sh SEE ALSO 94.Xr setgroups 2 , 95.Xr initgroups 3 , 96.Xr sysconf 3 97.Sh STANDARDS 98The 99.Fn getgroups 100system call conforms to 101.St -p1003.1-2008 . 102.Sh HISTORY 103The 104.Fn getgroups 105system call appeared in 106.Bx 4.2 . 107