.\" .\" Copyright (C) 2001 Chad David . All rights reserved. .\" Copyright (C) 2023 Olivier Certner .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice(s), this list of conditions and the following disclaimer as .\" the first lines of this file unmodified other than the possible .\" addition of one or more copyright notices. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice(s), this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY .\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED .\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE .\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY .\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES .\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR .\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER .\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH .\" DAMAGE. .\" .Dd October 31, 2024 .Dt GROUPMEMBER 9 .Os .Sh NAME .Nm groupmember .Nd checks if credentials mandate some group membership .Sh SYNOPSIS .In sys/param.h .In sys/ucred.h .Ft bool .Fn groupmember "gid_t gid" "const struct ucred *cred" .Ft bool .Fn realgroupmember "gid_t gid" "const struct ucred *cred" .Sh DESCRIPTION The .Fn groupmember function checks if credentials .Fa cred indicate that the associated subject or object is a member of the group designated by the group ID .Fa gid . .Pp Considered groups in .Fa cred are the effective and supplementary groups. The real group is not taken into account. .Pp Function .Fn realgroupmember works the same except that it considers instead the real and supplementary groups, and not the effective one. .Sh RETURN VALUES The .Fn groupmember and .Fn realgroupmember functions return .Dv true if the given credentials indicate membership of the group .Fa gid , or .Dv false otherwise. .Sh SEE ALSO .Xr getgroups 2 , .Xr setgroups 2 .Sh AUTHORS This manual page was initially written by .An -nosplit .An Chad David Aq Mt davidc@acns.ab.ca and was revised by .An Olivier Certner Aq Mt olce.freebsd@certner.fr .