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.Dd January 21, 2011 29.Dt GETGROUPS 2 30.Os 31.Sh NAME 32.Nm getgroups 33.Nd get group access list 34.Sh LIBRARY 35.Lb libc 36.Sh SYNOPSIS 37.In unistd.h 38.Ft int 39.Fn getgroups "int gidsetlen" "gid_t *gidset" 40.Sh DESCRIPTION 41The 42.Fn getgroups 43system call 44gets the current group access list of the user process 45and stores it in the array 46.Fa gidset . 47The 48.Fa gidsetlen 49argument 50indicates the number of entries that may be placed in 51.Fa gidset . 52The 53.Fn getgroups 54system call 55returns the actual number of groups returned in 56.Fa gidset . 57At least one and as many as {NGROUPS_MAX}+1 values may be returned. 58If 59.Fa gidsetlen 60is zero, 61.Fn getgroups 62returns the number of supplementary group IDs associated with 63the calling process without modifying the array pointed to by 64.Fa gidset . 65.Pp 66The value of 67.Dv {NGROUPS_MAX} 68should be obtained using 69.Xr sysconf 3 70to avoid hard-coding it into the executable. 71.Sh RETURN VALUES 72A successful call returns the number of groups in the group set. 73A value of -1 indicates that an error occurred, and the error 74code is stored in the global variable 75.Va errno . 76.Sh ERRORS 77The possible errors for 78.Fn getgroups 79are: 80.Bl -tag -width Er 81.It Bq Er EINVAL 82The argument 83.Fa gidsetlen 84is smaller than the number of groups in the group set. 85.It Bq Er EFAULT 86The argument 87.Fa gidset 88specifies 89an invalid address. 90.El 91.Sh SEE ALSO 92.Xr setgroups 2 , 93.Xr initgroups 3 , 94.Xr sysconf 3 95.Sh STANDARDS 96The 97.Fn getgroups 98system call conforms to 99.St -p1003.1-2008 . 100.Sh HISTORY 101The 102.Fn getgroups 103system call appeared in 104.Bx 4.2 . 105