mirror of https://github.com/mkerrisk/man-pages
84 lines
3.1 KiB
Plaintext
84 lines
3.1 KiB
Plaintext
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.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "SEEKDIR" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" seekdir
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.SH NAME
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seekdir \- set the position of a directory stream
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.SH SYNOPSIS
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.LP
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\fB#include <dirent.h>
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.br
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.sp
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void seekdir(DIR *\fP\fIdirp\fP\fB, long\fP \fIloc\fP\fB); \fP
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\fB
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.br
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\fP
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.SH DESCRIPTION
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.LP
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The \fIseekdir\fP() function shall set the position of the next \fIreaddir\fP()
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operation on the directory stream specified by \fIdirp\fP to the position
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specified by \fIloc\fP. The value of \fIloc\fP should
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have been returned from an earlier call to \fItelldir\fP(). The new
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position reverts to
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the one associated with the directory stream when \fItelldir\fP()
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was performed.
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.LP
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If the value of \fIloc\fP was not obtained from an earlier call to
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\fItelldir\fP(), or
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if a call to \fIrewinddir\fP() occurred between the call to \fItelldir\fP()
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and the call to \fIseekdir\fP(), the results of subsequent calls to
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\fIreaddir\fP() are unspecified.
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.SH RETURN VALUE
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.LP
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The \fIseekdir\fP() function shall not return a value.
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.SH ERRORS
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.LP
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No errors are defined.
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.LP
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\fIThe following sections are informative.\fP
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.SH EXAMPLES
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.LP
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None.
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.SH APPLICATION USAGE
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.LP
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None.
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.SH RATIONALE
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.LP
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The original standard developers perceived that there were restrictions
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on the use of the \fIseekdir\fP() and \fItelldir\fP() functions related
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to implementation details, and for that reason these functions
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need not be supported on all POSIX-conforming systems. They are required
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on implementations supporting the XSI extension.
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.LP
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One of the perceived problems of implementation is that returning
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to a given point in a directory is quite difficult to describe
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formally, in spite of its intuitive appeal, when systems that use
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B-trees, hashing functions, or other similar mechanisms to order
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their directories are considered. The definition of \fIseekdir\fP()
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and \fItelldir\fP()
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does not specify whether, when using these interfaces, a given directory
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entry will be seen at all, or more than once.
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.LP
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On systems not supporting these functions, their capability can sometimes
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be accomplished by saving a filename found by \fIreaddir\fP() and
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later using \fIrewinddir\fP() and a
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loop on \fIreaddir\fP() to relocate the position from which the filename
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was saved.
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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\fIopendir\fP() , \fIreaddir\fP() , \fItelldir\fP() , the Base Definitions
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volume of IEEE\ Std\ 1003.1-2001, \fI<dirent.h>\fP, \fI<stdio.h>\fP,
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\fI<sys/types.h>\fP
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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