PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

NAME

       seekdir — set the position of a directory stream

SYNOPSIS

       #include <dirent.h>

       void seekdir(DIR *dirp, long loc);

DESCRIPTION

       The  seekdir()  function  shall  set the position of the next readdir() operation on the directory stream
       specified by dirp to the position specified by loc.  The value of loc should have been returned  from  an
       earlier call to telldir() using the same directory stream. The new position reverts to the one associated
       with the directory stream when telldir() was performed.

       If  the  value  of  loc  was  not obtained from an earlier call to telldir(), or if a call to rewinddir()
       occurred between the call to telldir() and the call to seekdir(), the  results  of  subsequent  calls  to
       readdir() are unspecified.

RETURN VALUE

       The seekdir() function shall not return a value.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       The  original  standard developers perceived that there were restrictions on the use of the seekdir() and
       telldir() functions related to implementation details, and for that reason these functions  need  not  be
       supported  on  all  POSIX-conforming  systems.  They  are  required on implementations supporting the XSI
       option.

       One of the perceived problems of implementation is that returning to a given  point  in  a  directory  is
       quite  difficult  to  describe formally, in spite of its intuitive appeal, when systems that use B-trees,
       hashing functions, or other similar mechanisms to order their directories are considered. The  definition
       of seekdir() and telldir() does not specify whether, when using these interfaces, a given directory entry
       will be seen at all, or more than once.

       On  systems  not  supporting  these functions, their capability can sometimes be accomplished by saving a
       filename found by readdir() and later using rewinddir() and a loop on readdir() to relocate the  position
       from which the filename was saved.

FUTURE DIRECTIONS

       None.

SEE ALSO

       fdopendir(), readdir(), telldir()

       The Base Definitions volume of POSIX.1‐2017, <dirent.h>, <sys_types.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for  Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical  and  Electronics
       Engineers, Inc and The Open Group.  In the event of any discrepancy between this version and the original
       IEEE  and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document.
       The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are most likely to have  been  introduced
       during   the   conversion  of  the  source  files  to  man  page  format.  To  report  such  errors,  see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                                   2017                                       SEEKDIR(3POSIX)