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SEEKDIR(3P)                POSIX Programmer's Manual               SEEKDIR(3P)

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(). The new position reverts to the one associ-
       ated 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  imple-
       mentation details, and for that reason these functions need not be sup-
       ported on all POSIX-conforming systems. They are required on  implemen-
       tations 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 some-
       times 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(3P)