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 .