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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 maximum needed  size  for  buf  can  be  found  using  sysconf(3)  with  the  argument
       _SC_GETGR_R_SIZE_MAX.

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

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 3.35 of the Linux man-pages project.  A  description  of  the
       project,  and information about reporting bugs, can be found at http://man7.org/linux/man-
       pages/.

                                            2010-10-21                                GETGRNAM(3)