GETGRENT(3)                         Linux Programmer's Manual                         GETGRENT(3)



NAME
       getgrent, setgrent, endgrent - get group file entry

SYNOPSIS
       #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 pass the returned pointer to free(3).)

ERRORS
       EAGAIN The  service  was  temporarily  unavailable;  try again later.  For NSS backends in
              glibc this indicates a temporary error talking to the backend.  The error may  cor‐
              rect itself, retrying later is suggested.

       EINTR  A signal was caught.

       EIO    I/O error.

       EMFILE The calling process already has too many open files.

       ENFILE Too many open files in the system.

       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
   Multithreading (see pthreads(7))
       The getgrent() function is not thread-safe.

       The setgrent() and endgrent() functions are thread-safe.

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

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

COLOPHON
       This  page  is  part of release 3.74 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/.



                                            2014-10-02                                GETGRENT(3)