initgroups - Man Page

initialize the supplementary group access list

Synopsis

#include <sys/types.h>
#include <grp.h>

int initgroups(const char *user, gid_t group);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

initgroups():

    Since glibc 2.19:
        _DEFAULT_SOURCE
    glibc 2.19 and earlier:
        _BSD_SOURCE

The initgroups() function initializes the group access list by reading the group database /etc/group and using all groups of which user is a member. The additional group group is also added to the list.

The user argument must be non-NULL.

Return Value

The initgroups() function returns 0 on success. On error, -1 is returned, and errno is set to indicate the error.

Errors

ENOMEM: Insufficient memory to allocate group information structure.
EPERM: The calling process has insufficient privilege. See the underlying system call setgroups(2).