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GETGRENT(3)                Library Functions Manual                GETGRENT(3)



NAME
       getgrent, getgrgid, getgrnam, setgrent, endgrent - get group file entry

SYNOPSIS
       #include <&lt;grp.h>&gt;

       struct group *getgrent();

       struct group *getgrgid(gid) int gid;

       struct group *getgrnam(name) char *name;

       int setgrent();

       int endgrent();

DESCRIPTION
       Getgrent,  getgrgid and getgrnam each return pointers to an object with
       the following structure containing the broken-out fields of a  line  in
       the group file.

              /* Copyright (C) 1991-2016 Free Software Foundation, Inc.
                 This file is part of the GNU C Library.

                 The GNU C Library is free software; you can redistribute it and/or
                 modify it under the terms of the GNU Lesser General Public
                 License as published by the Free Software Foundation; either
                 version 2.1 of the License, or (at your option) any later version.

                 The GNU C Library is distributed in the hope that it will be useful,
                 but WITHOUT ANY WARRANTY; without even the implied warranty of
                 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
                 Lesser General Public License for more details.

                 You should have received a copy of the GNU Lesser General Public
                 License along with the GNU C Library; if not, see
                 <http://www.gnu.org/licenses/>;.  */

              /*
               *   POSIX Standard: 9.2.1 Group Database Access  <grp.h>
               */

              #ifndef   _GRP_H
              #define   _GRP_H    1

              #include <features.h>

              __BEGIN_DECLS

              #include <bits/types.h>

              #define __need_size_t
              #include <stddef.h>


              /* For the Single Unix specification we must define this type here.  */
              #if (defined __USE_XOPEN || defined __USE_XOPEN2K) && !defined __gid_t_defined
              typedef __gid_t gid_t;
              # define __gid_t_defined
              #endif

              /* The group structure.   */
              struct group
                {
                  char *gr_name;       /* Group name. */
                  char *gr_passwd;          /* Password.   */
                  __gid_t gr_gid;      /* Group ID.   */
                  char **gr_mem;       /* Member list.     */
                };


              #ifdef __USE_MISC
              # define __need_FILE
              # include <stdio.h>
              #endif


              #if defined __USE_MISC || defined __USE_XOPEN_EXTENDED
              /* Rewind the group-file stream.

                 This function is a possible cancellation point and therefore not
                 marked with __THROW.  */
              extern void setgrent (void);

              /* Close the group-file stream.

                 This function is a possible cancellation point and therefore not
                 marked with __THROW.  */
              extern void endgrent (void);

              /* Read an entry from the group-file stream, opening it if necessary.

                 This function is a possible cancellation point and therefore not
                 marked with __THROW.  */
              extern struct group *getgrent (void);
              #endif

              #ifdef    __USE_MISC
              /* Read a group entry from STREAM.

                 This function is not part of POSIX and therefore no official
                 cancellation point.  But due to similarity with an POSIX interface
                 or due to the implementation it is a cancellation point and
                 therefore not marked with __THROW.  */
              extern struct group *fgetgrent (FILE *__stream);
              #endif

              #ifdef __USE_GNU
              /* Write the given entry onto the given stream.

                 This function is not part of POSIX and therefore no official
                 cancellation point.  But due to similarity with an POSIX interface
                 or due to the implementation it is a cancellation point and
                 therefore not marked with __THROW.  */
              extern int putgrent (const struct group *__restrict __p,
                             FILE *__restrict __f);
              #endif

              /* Search for an entry with a matching group ID.

                 This function is a possible cancellation point and therefore not
                 marked with __THROW.  */
              extern struct group *getgrgid (__gid_t __gid);

              /* Search for an entry with a matching group name.

                 This function is a possible cancellation point and therefore not
                 marked with __THROW.  */
              extern struct group *getgrnam (const char *__name);

              #ifdef __USE_POSIX

              # ifdef __USE_MISC
              /* Reasonable value for the buffer sized used in the reentrant
                 functions below.  But better use `sysconf'.  */
              #  define NSS_BUFLEN_GROUP    1024
              # endif

              /* Reentrant versions of some of the functions above.

                 PLEASE NOTE: the `getgrent_r' function is not (yet) standardized.
                 The interface may change in later versions of this library.  But
                 the interface is designed following the principals used for the
                 other reentrant functions so the chances are good this is what the
                 POSIX people would choose.

                 This function is not part of POSIX and therefore no official
                 cancellation point.  But due to similarity with an POSIX interface
                 or due to the implementation it is a cancellation point and
                 therefore not marked with __THROW.  */

              # ifdef __USE_GNU
              extern int getgrent_r (struct group *__restrict __resultbuf,
                               char *__restrict __buffer, size_t __buflen,
                               struct group **__restrict __result);
              # endif

              /* Search for an entry with a matching group ID.

                 This function is a possible cancellation point and therefore not
                 marked with __THROW.  */
              extern int getgrgid_r (__gid_t __gid, struct group *__restrict __resultbuf,
                               char *__restrict __buffer, size_t __buflen,
                               struct group **__restrict __result);

              /* Search for an entry with a matching group name.

                 This function is a possible cancellation point and therefore not
                 marked with __THROW.  */
              extern int getgrnam_r (const char *__restrict __name,
                               struct group *__restrict __resultbuf,
                               char *__restrict __buffer, size_t __buflen,
                               struct group **__restrict __result);

              # ifdef   __USE_MISC
              /* Read a group entry from STREAM.  This function is not standardized
                 an probably never will.

                 This function is not part of POSIX and therefore no official
                 cancellation point.  But due to similarity with an POSIX interface
                 or due to the implementation it is a cancellation point and
                 therefore not marked with __THROW.  */
              extern int fgetgrent_r (FILE *__restrict __stream,
                             struct group *__restrict __resultbuf,
                             char *__restrict __buffer, size_t __buflen,
                             struct group **__restrict __result);
              # endif

              #endif    /* POSIX or reentrant */


              #ifdef    __USE_MISC

              # define __need_size_t
              # include <stddef.h>

              /* Set the group set for the current user to GROUPS (N of them).  */
              extern int setgroups (size_t __n, const __gid_t *__groups) __THROW;

              /* Store at most *NGROUPS members of the group set for USER into
                 *GROUPS.  Also include GROUP.  The actual number of groups found is
                 returned in *NGROUPS.  Return -1 if the if *NGROUPS is too small.

                 This function is not part of POSIX and therefore no official
                 cancellation point.  But due to similarity with an POSIX interface
                 or due to the implementation it is a cancellation point and
                 therefore not marked with __THROW.  */
              extern int getgrouplist (const char *__user, __gid_t __group,
                              __gid_t *__groups, int *__ngroups);

              /* Initialize the group set for the current user
                 by reading the group database and using all groups
                 of which USER is a member.  Also include GROUP.

                 This function is not part of POSIX and therefore no official
                 cancellation point.  But due to similarity with an POSIX interface
                 or due to the implementation it is a cancellation point and
                 therefore not marked with __THROW.  */
              extern int initgroups (const char *__user, __gid_t __group);

              #endif /* Use misc.  */

              __END_DECLS

              #endif /* grp.h  */

       The members of this structure are:

       gr_name
              The name of the group.
       gr_passwd
              The encrypted password of the group.
       gr_gid The numerical group-ID.
       gr_mem Null-terminated  vector  of  pointers  to  the individual member
              names.

       Getgrent simply reads the next line while getgrgid and getgrnam  search
       until  a  matching  gid or name is found (or until EOF is encountered).
       Each routine picks up where the others leave off  so  successive  calls
       may be used to search the entire file.

       A  call to setgrent has the effect of rewinding the group file to allow
       repeated searches.  Endgrent may be called to close the group file when
       processing is complete.

FILES
       /etc/group

SEE ALSO
       getlogin(3), getpwent(3), group(5)

DIAGNOSTICS
       A null pointer (0) is returned on EOF or error.

BUGS
       All  information  is contained in a static area so it must be copied if
       it is to be saved.



                                                                   GETGRENT(3)