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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  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 3.27 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)