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SEEKDIR(3P) POSIX Programmer's Manual SEEKDIR(3P)
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.
seekdir — set the position of a directory stream
#include <dirent.h>
void seekdir(DIR *dirp, long loc);
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.
The seekdir() function shall not return a value.
No errors are defined.
The following sections are informative.
None.
None.
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.
None.
fdopendir(3p), readdir(3p), telldir(3p)
The Base Definitions volume of POSIX.1‐2017, dirent.h(0p),
sys_types.h(0p)
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(3P)
Pages that refer to this page: dirent.h(0p), telldir(3p)