getgrnam(3)                                           Library Functions Manual                                          getgrnam(3)

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

       Standard C library (libc, -lc)

       #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 buf[restrict .buflen], size_t buflen,
                      struct group **restrict result);
       int getgrgid_r(gid_t gid, struct group *restrict grp,
                      char buf[restrict .buflen], size_t buflen,
                      struct group **restrict result);

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

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

       The  getgrnam()  function returns a pointer to a structure containing the broken-out fields of the record in the group data‐
       base (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  data‐
       base 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 re‐
       trieved 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


       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.)

       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 get‐
       grnam().  (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.

       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.

              local group database file

       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(), getgrgid_r() │ Thread safety │ MT-Safe locale                                                                │

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

       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  oth‐

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

Linux man-pages 6.03                                         2023-02-05                                                 getgrnam(3)