1.\" Copyright (c) 1983, 1991, 1993, 1994 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 August 1, 2025 29.Dt SETGROUPS 2 30.Os 31.Sh NAME 32.Nm setgroups 33.Nd set group access list 34.Sh LIBRARY 35.Lb libc 36.Sh SYNOPSIS 37.In sys/param.h 38.In unistd.h 39.Ft int 40.Fn setgroups "int ngroups" "const gid_t *gidset" 41.Sh DESCRIPTION 42The 43.Fn setgroups 44system call 45sets the supplementary group list of the current user process 46according to the array 47.Fa gidset . 48The 49.Fa ngroups 50argument 51indicates the number of entries in the array and must be no 52more than 53.Dv {NGROUPS_MAX} . 54The 55.Fa ngroups 56argument may be set to 0 to clear the supplementary group list. 57.Pp 58Only the super-user may set a new supplementary group list. 59.Sh RETURN VALUES 60.Rv -std setgroups 61.Sh ERRORS 62The 63.Fn setgroups 64system call will fail if: 65.Bl -tag -width Er 66.It Bq Er EPERM 67The caller is not the super-user. 68.It Bq Er EINVAL 69The number specified in the 70.Fa ngroups 71argument is larger than the 72.Dv {NGROUPS_MAX}+1 73limit. 74.It Bq Er EFAULT 75The address specified for 76.Fa gidset 77is outside the process 78address space. 79.El 80.Sh SEE ALSO 81.Xr getgroups 2 , 82.Xr initgroups 3 83.Sh HISTORY 84The 85.Fn setgroups 86system call appeared in 87.Bx 4.2 . 88.Pp 89Before 90.Fx 15.0 , 91the 92.Fn setgroups 93system call would set the effective group ID for the process to the first 94element of 95.Fa gidset . 96