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initgroups

initialize the supplementary group access list

#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.

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

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

/etc/group
group database file

For an explanation of the terms used in this section, see attributes(7).

Interface Attribute Value
initgroups () Thread safety MT-Safe locale

SVr4, 4.3BSD.

getgroups(2), setgroups(2), credentials(7)

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