initgroups - initialize the supplementary group access list

       For an explanation of the terms used in this section, see attributes(7).
       ┌──────────────────────────────────────────────────────────────────────┬───────────────┬────────────────┐
       │ Interface                                                            │ Attribute     │ Value          │
       ├──────────────────────────────────────────────────────────────────────┼───────────────┼────────────────┤
       │ initgroups()                                                         │ Thread safety │ MT-Safe locale │
       └──────────────────────────────────────────────────────────────────────┴───────────────┴────────────────┘

       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.

ENOMEM Insufficient memory to allocate group information structure.

       EPERM  The calling process has insufficient privilege.  See the underlying system call setgroups(2).

/etc/group
              group database file

       SVr4, 4.3BSD.

       Standard C library (libc, -lc)

       initgroups - initialize the supplementary group access list

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

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

Linux man-pages 6.9.1                              2024-05-02                                      initgroups(3)

       None.

#include<sys/types.h>#include<grp.h>intinitgroups(constchar*user,gid_tgroup);

   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