.\" Copyright (C) 2014, Michael Kerrisk <mtk.manpages@gmail.com>
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.TH group_member 3 2023-10-31 "Linux man-pages 6.06"
.SH NAME
group_member \- test whether a process is in a group
.SH LIBRARY
Standard C library
.RI ( libc ", " \-lc )
.SH SYNOPSIS
.nf
.B #include <unistd.h>
.P
.BI "int group_member(gid_t " gid );
.fi
.P
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.P
.BR group_member ():
.nf
    _GNU_SOURCE
.fi
.SH DESCRIPTION
The
.BR group_member ()
function tests whether any of the caller's supplementary group IDs
(as returned by
.BR getgroups (2))
matches
.IR gid .
.SH RETURN VALUE
The
.BR group_member ()
function returns nonzero if any of the caller's
supplementary group IDs matches
.IR gid ,
and zero otherwise.
.SH STANDARDS
GNU.
.SH SEE ALSO
.BR getgid (2),
.BR getgroups (2),
.BR getgrouplist (3),
.BR group (5)