NAME

       getgrnam, getgrnam_r, getgrgid, getgrgid_r - get group file entry

SYNOPSIS

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

       struct group *getgrnam(const char *name);

       struct group *getgrgid(gid_t gid);

       int getgrnam_r(const char *name, struct group *grp,
                 char *buf, size_t buflen, struct group **result);

       int getgrgid_r(gid_t gid, struct group *grp,
                 char *buf, size_t buflen, struct group **result);

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

       getgrnam_r(), getgrgid_r():
           _POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE || _BSD_SOURCE || _SVID_SOURCE || _POSIX_SOURCE

DESCRIPTION

       The  getgrnam()  function returns a pointer to a structure containing the broken-out fields of the record
       in the group database (e.g., the local group file /etc/group, NIS, and LDAP) that matches the group  name
       name.

       The  getgrgid()  function returns a pointer to a structure containing the broken-out fields of the record
       in the group database that matches the group ID gid.

       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;        /* group members */
           };

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

       The getgrnam_r() and getgrgid_r() functions obtain the same information as getgrnam() and getgrgid(), but
       store the retrieved group structure in the space pointed to by grp.  The string fields pointed to by  the
       members  of the group structure are stored in the buffer buf of size buflen.  A pointer to the result (in
       case of success) or NULL (in case no entry was found or an error occurred) is stored in *result.

       The call

           sysconf(_SC_GETGR_R_SIZE_MAX)

       returns either -1, without changing errno, or an initial suggested size for buf.  (If this  size  is  too
       small, the call fails with ERANGE, in which case the caller can retry with a larger buffer.)

RETURN VALUE

       The  getgrnam()  and  getgrgid() functions return a pointer to a group structure, or NULL if the matching
       entry is not found or an error occurs.  If an error occurs, errno is set appropriately.  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(3),
       getgrgid(), or getgrnam().  (Do not pass the returned pointer to free(3).)

       On success, getgrnam_r() and getgrgid_r() return zero, and set *result to  grp.   If  no  matching  group
       record  was found, these functions return 0 and store NULL in *result.  In case of error, an error number
       is returned, and NULL is stored in *result.

ERRORS

       0 or ENOENT or ESRCH or EBADF or EPERM or ...
              The given name or gid was not found.

       EINTR  A signal was caught.

       EIO    I/O error.

       EMFILE The maximum number (OPEN_MAX) of files was open already in the calling process.

       ENFILE The maximum number of files was open already in the system.

       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 getgrnam() and getgrgid() functions are not thread-safe.

       The getgrnam_r() and getgrgid_r() functions are thread-safe.

CONFORMING TO

       SVr4, 4.3BSD, POSIX.1-2001.

NOTES

       The formulation given above under "RETURN VALUE" is from POSIX.1-2001.  It does not call "not  found"  an
       error,  hence  does  not  specify  what  value  errno  might  have  in this situation.  But that makes it
       impossible to recognize errors.  One might argue that according to POSIX errno should be  left  unchanged
       if  an  entry is not found.  Experiments on various UNIX-like systems shows that lots of different values
       occur in this situation: 0, ENOENT, EBADF, ESRCH, EWOULDBLOCK, EPERM and probably others.

SEE ALSO

       endgrent(3), fgetgrent(3), getgrent(3), getpwnam(3), setgrent(3), group(5)

COLOPHON

       This page is part of release 3.54 of the Linux man-pages project.  A  description  of  the  project,  and
       information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.

                                                   2013-07-22                                        GETGRNAM(3)