getgroups(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

getgroups() 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 greater 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.

setgroups() 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. This function may be invoked only by the super-user.

RETURN VALUES

Upon successful completion, getgroups() returns the number of supplementary group IDs set for the calling process and setgroups() returns the value 0. Otherwise, a value of −1 is returned and errno is set to indicate the error.

ERRORS

getgroups() 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.

setgroups() 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.

Either call will fail if:

EFAULT A referenced part of the array pointed to by grouplist is an illegal address.

Museum