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SETGROUPS(2) FreeBSD System Calls Manual SETGROUPS(2)
NAME
setgroups - set group access list
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/param.h>
#include <unistd.h>
int
setgroups(int ngroups, const gid_t *gidset);
DESCRIPTION
The setgroups() system call sets the group access list of the current
user process according to the array gidset. The ngroups argument
indicates the number of entries in the array and must be no more than
{NGROUPS_MAX}+1.
Only the super-user may set a new group list.
The first entry of the group array (gidset[0]) is used as the effective
group-ID for the process. This entry is over-written when a setgid
program is run. To avoid losing access to the privileges of the
gidset[0] entry, it should be duplicated later in the group array. By
convention, this happens because the group value indicated in the
password file also appears in /etc/group. The group value in the
password file is placed in gidset[0] and that value then gets added a
second time when the /etc/group file is scanned to create the group set.
RETURN VALUES
The setgroups() function returns the value 0 if successful; otherwise the
value -1 is returned and the global variable errno is set to indicate the
error.
ERRORS
The setgroups() system call will fail if:
[EPERM] The caller is not the super-user.
[EINVAL] The number specified in the ngroups argument is larger
than the {NGROUPS_MAX}+1 limit.
[EFAULT] The address specified for gidset is outside the
process address space.
SEE ALSO
getgroups(2), initgroups(3)
HISTORY
The setgroups() system call appeared in 4.2BSD.
FreeBSD 14.2-RELEASE January 19, 2018 FreeBSD 14.2-RELEASE