getgrnam(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | FILES | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

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

NAME         top

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

SYNOPSIS         top

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

       struct group *getgrnam(const char *name);
       struct group *getgrgid(gid_t gid);

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

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

       getgrnam_r(), getgrgid_r():
           _POSIX_C_SOURCE
               || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION         top

       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;         /* NULL-terminated array of pointers
                                          to names of 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         top

       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 to indicate the
       error.  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         top

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

       EINTR  A signal was caught; see signal(7).

       EIO    I/O error.

       EMFILE The per-process limit on the number of open file
              descriptors has been reached.

       ENFILE The system-wide limit on the total number of open files
              has been reached.

       ENOMEM Insufficient memory to allocate group structure.

       ERANGE Insufficient buffer space supplied.

FILES         top

       /etc/group
              local group database file

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).

       ┌──────────────┬───────────────┬─────────────────────────────────┐
       │Interface     Attribute     Value                           │
       ├──────────────┼───────────────┼─────────────────────────────────┤
       │getgrnam()    │ Thread safety │ MT-Unsafe race:grnam locale     │
       ├──────────────┼───────────────┼─────────────────────────────────┤
       │getgrgid()    │ Thread safety │ MT-Unsafe race:grgid locale     │
       ├──────────────┼───────────────┼─────────────────────────────────┤
       │getgrnam_r(), │ Thread safety │ MT-Safe locale                  │
       │getgrgid_r()  │               │                                 │
       └──────────────┴───────────────┴─────────────────────────────────┘

CONFORMING TO         top

       POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.

NOTES         top

       The formulation given above under "RETURN VALUE" is from POSIX.1.
       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 show that lots of
       different values occur in this situation: 0, ENOENT, EBADF,
       ESRCH, EWOULDBLOCK, EPERM, and probably others.

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 5.11 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

                               2021-03-22                    GETGRNAM(3)

Pages that refer to this page: getent(1)git-daemon(1)fgetgrent(3)getgrent(3)getgrent_r(3)getpwnam(3)getspnam(3)group(5)nscd(8)