getgrent

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

       struct group *getgrent(void);

       void setgrent(void);

       void endgrent(void);

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

       setgrent():
           _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 500 ||
           _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED ||
           /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L

       getgrent(), endgrent():
           _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 500 ||
           _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED

DESCRIPTION
       The getgrent() function returns a pointer to a structure containing the
       broken-out fields of a record in the group database  (e.g.,  the  local
       group  file  /etc/group,  NIS, and LDAP).  The first time getgrent() is
       called, it returns the first entry; thereafter, it  returns  successive
       entries.

       The setgrent() function rewinds to the beginning of the group database,
       to allow repeated scans.

       The endgrent() function is used to close the group database  after  all
       processing has been performed.

       The group structure is defined in <grp.h> as follows:

           struct group {
               char   *gr_name;        /* group name */
               char   *gr_passwd;      /* group password */
               gid_t   gr_gid;         /* group ID */
               char  **gr_mem;         /* NULL-terminated array of pointers
                                          to names of group members */
           };

       For more information about the fields of this structure, see group(5).

RETURN VALUE
       The getgrent() function returns a pointer to a group structure, or NULL
       if there are no more entries or an error occurs.

       Upon error, errno may be set.  If one wants to check  errno  after  the
       call, it should be set to zero before the call.

       The  return value may point to a static area, and may be overwritten by
       subsequent calls to getgrent(), getgrgid(3), or getgrnam(3).   (Do  not
       EMFILE The per-process limit on the number of open file descriptors has
              been reached.

       ENFILE The system-wide limit on the total number of open files has been
              reached.

       ENOENT A necessary input file cannot be found.   For  NSS  backends  in
              glibc this indicates the backend is not correctly configured.

       ENOMEM Insufficient memory to allocate group structure.

       ERANGE Insufficient buffer space supplied.

FILES
       /etc/group
              local group database file

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

       +------------+---------------+-----------------------------+
       |Interface   | Attribute     | Value                       |
       +------------+---------------+-----------------------------+
       |getgrent()  | Thread safety | MT-Unsafe race:grent        |
       |            |               | race:grentbuf locale        |
       +------------+---------------+-----------------------------+
       |setgrent(), | Thread safety | MT-Unsafe race:grent locale |
       |endgrent()  |               |                             |
       +------------+---------------+-----------------------------+
       In  the  above  table, grent in race:grent signifies that if any of the
       functions setgrent(), getgrent(), or endgrent() are used in parallel in
       different threads of a program, then data races could occur.

CONFORMING TO
       POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.

SEE ALSO
       fgetgrent(3), getgrent_r(3), getgrgid(3), getgrnam(3), getgrouplist(3),
       putgrent(3), group(5)

COLOPHON
       This page is part of release 4.04 of the Linux  man-pages  project.   A
       description  of  the project, information about reporting bugs, and the
       latest    version    of    this    page,    can     be     found     at
       http://www.kernel.org/doc/man-pages/.

                                  2015-12-28                       GETGRENT(3)
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