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



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  getgrnam_r()  and getgrgid_r() functions obtain the same information, but store the retrieved group structure in the
       space pointed to by grp.  This group structure contains pointers to strings, and these strings 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 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 */
           };

       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 3.25 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/.



                                                           2009-03-30                                                GETGRNAM(3)