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 .

IEEE/The Open Group                                   2003                                            SEEKDIR(P)