telldir - return current location in directory stream

       For an explanation of the terms used in this section, see attributes(7).
       ┌─────────────────────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                                                                   │ Attribute     │ Value   │
       ├─────────────────────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │ telldir()                                                                   │ Thread safety │ MT-Safe │
       └─────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

       The telldir() function returns the current location associated with the directory stream dirp.

EBADF  Invalid directory stream descriptor dirp.

       POSIX.1-2001, 4.3BSD.

       Up  to glibc 2.1.1, the return type of telldir() was off_t.  POSIX.1-2001 specifies long, and this is the
       type used since glibc 2.1.2.

       In early filesystems, the value returned by telldir() was  a  simple  file  offset  within  a  directory.
       Modern  filesystems  use  tree or hash structures, rather than flat tables, to represent directories.  On
       such filesystems, the value returned by telldir() (and used internally by readdir(3)) is a "cookie"  that
       is used by the implementation to derive a position within a directory.  Application programs should treat
       this strictly as an opaque value, making no assumptions about its contents.

       Standard C library (libc, -lc)

       telldir - return current location in directory stream

       On success, the telldir() function returns the current location in the directory stream.  On error, -1 is
       returned, and errno is set to indicate the error.

closedir(3), opendir(3), readdir(3), rewinddir(3), scandir(3), seekdir(3)

Linux man-pages 6.9.1                              2024-05-02                                         telldir(3)

       POSIX.1-2008.

#include<dirent.h>longtelldir(DIR*dirp);

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

       telldir():
           _XOPEN_SOURCE
              || /* glibc >= 2.19: */ _DEFAULT_SOURCE
              || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE