GETGROUPS(2)

NAME
getgroups, setgroups - get/set list of supplementary group IDs

SYNOPSIS
#include <unistd.h>

int getgroups(int size, gid_t list[]);

#define __USE_BSD
#include <grp.h>

int setgroups(size_t size, const gid_t *list);

DESCRIPTION

getgroups
    Up to size supplementary groups are returned in list. If size is zero, list is not modified, but the total number of supplementary groups for the process is returned.

setgroups
    Sets the supplementary groups for the process. Only the super-user may use this function.

RETURN VALUE

getgroups
    On success, the number of supplementary group IDs is returned. On error, -1 is returned, and errno is set appropriately.

setgroups
    On success, zero is returned. On error, -1 is returned, and errno is set appropriately.

ERRORS

EFAULT
    list has an invalid address.

EPERM
    For setgroups, the user is not the super-user.

EINVAL
    For setgroups, size is greater than NGROUPS (32 for Linux 2.0.32). For getgroups, size is less than the number of supplementary group IDs, but is not zero.

CONFORMING TO
SVr4, SVID (issue 4 only; these calls were not present in SVr3), X/OPEN, 4.3BSD. The getgroups function is in POSIX.1. Since setgroups requires privilege, it is not covered by POSIX.1.

BUGS
The __USE_BSD flag probably shouldn't be required for setgroups.

SEE ALSO
initgroups(3), getgid(2), setgid(2)