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(). 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 extension.

       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

       opendir() , readdir() , telldir() , the Base Definitions volume  of  IEEE Std 1003.1-2001,
       <dirent.h>, <stdio.h>, <sys/types.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2003 Edition, Standard for Information Technology  --  Portable  Operating  System
       Interface  (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 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 .