setgroups(2)
NAME
getgroups, setgroups - get or set supplementary group access
list IDs
SYNOPSIS
#include <unistd.h>
int getgroups(int gidsetsize, gid_t *grouplist);
int setgroups(int ngroups, const gid_t *grouplist);
DESCRIPTION
The getgroups() function gets the current supplemental group
access list of the calling process and stores the result in
the array of group IDs specified by grouplist. This array
has gidsetsize entries and must be large enough to contain
the entire list. This list cannot be larger than
NGROUPS_MAX. If gidsetsize equals 0, getgroups() will return
the number of groups to which the calling process belongs
without modifying the array pointed to by grouplist.
The setgroups() function sets the supplementary group access
list of the calling process from the array of group IDs
specified by grouplist. The number of entries is specified
by ngroups and can not be greater than NGROUPS_MAX.
RETURN VALUES
Upon successful completion, getgroups() returns the number
of supplementary group IDs set for the calling process and
setgroups() returns 0. Otherwise, -1 is returned and errno
is set to indicate the error.
ERRORS
The getgroups() and setgroups() functions will fail if:
EFAULT
A referenced part of the array pointed to by grouplist
is an illegal address.
The getgroups() function will fail if:
EINVAL
The value of gidsetsize is non-zero and less than the
number of supplementary group IDs set for the calling
process.
The setgroups() function will fail if:
EINVAL
The value of ngroups is greater than NGROUPS_MAX.
EPERM The effective user of the calling process is not
super-user.
USAGE
Use of the setgroups() function requires superuser
privileges.
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| MT-Level | Async-Signal-Safe |
|_____________________________|_____________________________|
SEE ALSO
groups(1), chown(2), getuid(2), setuid(2), getgrnam(3C),
initgroups(3C), attributes(5)
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