281 lines
5.2 KiB
HTML
281 lines
5.2 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of FSEEK</TITLE>
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</HEAD><BODY>
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<H1>FSEEK</H1>
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Section: Linux Programmer's Manual (3)<BR>Updated: 2018-04-30<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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fgetpos, fseek, fsetpos, ftell, rewind - reposition a stream
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>#include <<A HREF="file:///usr/include/stdio.h">stdio.h</A>></B>
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<P>
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<B>int fseek(FILE *</B><I>stream</I><B>, long </B><I>offset</I><B>, int </B><I>whence</I><B>);</B>
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<P>
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<B>long ftell(FILE *</B><I>stream</I><B>);</B>
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<P>
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<B>void rewind(FILE *</B><I>stream</I><B>);</B>
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<P>
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<B>int fgetpos(FILE *</B><I>stream</I><B>, fpos_t *</B><I>pos</I><B>);</B>
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<P>
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<B>int fsetpos(FILE *</B><I>stream</I><B>, const fpos_t *</B><I>pos</I><B>);</B>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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The
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<B>fseek</B>()
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function sets the file position indicator for the stream pointed to by
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<I>stream</I>.
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The new position, measured in bytes, is obtained by adding
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<I>offset</I>
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bytes to the position specified by
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<I>whence</I>.
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If
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<I>whence</I>
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is set to
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<B>SEEK_SET</B>,
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<B>SEEK_CUR</B>,
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or
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<B>SEEK_END</B>,
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the offset is relative to the start of the file, the current position
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indicator, or end-of-file, respectively.
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A successful call to the
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<B>fseek</B>()
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function clears the end-of-file indicator for the stream and undoes
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any effects of the
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<B><A HREF="/cgi-bin/man/man2html?3+ungetc">ungetc</A></B>(3)
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function on the same stream.
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<P>
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The
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<B>ftell</B>()
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function obtains the current value of the file position indicator for the
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stream pointed to by
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<I>stream</I>.
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<P>
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The
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<B>rewind</B>()
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function sets the file position indicator for the stream pointed to by
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<I>stream</I>
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to the beginning of the file.
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It is equivalent to:
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<P>
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<DL COMPACT><DT id="1"><DD>
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(void) fseek(stream, 0L, SEEK_SET)
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</DL>
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<P>
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except that the error indicator for the stream is also cleared (see
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<B><A HREF="/cgi-bin/man/man2html?3+clearerr">clearerr</A></B>(3)).
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<P>
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The
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<B>fgetpos</B>()
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and
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<B>fsetpos</B>()
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functions are alternate interfaces equivalent to
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<B>ftell</B>()
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and
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<B>fseek</B>()
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(with
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<I>whence</I>
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set to
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<B>SEEK_SET</B>),
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setting and storing the current value of the file offset into or from the
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object referenced by
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<I>pos</I>.
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On some non-UNIX systems, an
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<I>fpos_t</I>
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object may be a complex object and these routines may be the only way to
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portably reposition a text stream.
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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The
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<B>rewind</B>()
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function returns no value.
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Upon successful completion,
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<B>fgetpos</B>(),
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<B>fseek</B>(),
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<B>fsetpos</B>()
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return 0,
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and
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<B>ftell</B>()
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returns the current offset.
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Otherwise, -1 is returned and
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<I>errno</I>
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is set to indicate the error.
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<A NAME="lbAF"> </A>
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<H2>ERRORS</H2>
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<DL COMPACT>
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<DT id="2"><B>EINVAL</B>
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<DD>
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The
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<I>whence</I>
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argument to
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<B>fseek</B>()
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was not
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<B>SEEK_SET</B>,
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<B>SEEK_END</B>,
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or
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<B>SEEK_CUR</B>.
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Or: the resulting file offset would be negative.
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<DT id="3"><B>ESPIPE</B>
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<DD>
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The file descriptor underlying
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<I>stream</I>
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is not seekable (e.g., it refers to a pipe, FIFO, or socket).
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</DL>
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<P>
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The functions
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<B>fgetpos</B>(),
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<B>fseek</B>(),
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<B>fsetpos</B>(),
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and
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<B>ftell</B>()
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may also fail and set
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<I>errno</I>
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for any of the errors specified for the routines
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<B><A HREF="/cgi-bin/man/man2html?3+fflush">fflush</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?2+fstat">fstat</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+lseek">lseek</A></B>(2),
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and
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<B><A HREF="/cgi-bin/man/man2html?3+malloc">malloc</A></B>(3).
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<A NAME="lbAG"> </A>
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<H2>ATTRIBUTES</H2>
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For an explanation of the terms used in this section, see
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<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
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<TABLE BORDER>
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<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
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<TR VALIGN=top><TD>
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<B>fseek</B>(),
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<B>ftell</B>(),
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<B>rewind</B>(),
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<BR>
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<B>fgetpos</B>(),
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<B>fsetpos</B>()
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</TD><TD>Thread safety</TD><TD>MT-Safe<BR></TD></TR>
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</TABLE>
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<P>
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<A NAME="lbAH"> </A>
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<H2>CONFORMING TO</H2>
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POSIX.1-2001, POSIX.1-2008, C89, C99.
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<A NAME="lbAI"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?2+lseek">lseek</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?3+fseeko">fseeko</A></B>(3)
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<A NAME="lbAJ"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="4"><A HREF="#lbAB">NAME</A><DD>
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<DT id="5"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="6"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="7"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="8"><A HREF="#lbAF">ERRORS</A><DD>
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<DT id="9"><A HREF="#lbAG">ATTRIBUTES</A><DD>
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<DT id="10"><A HREF="#lbAH">CONFORMING TO</A><DD>
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<DT id="11"><A HREF="#lbAI">SEE ALSO</A><DD>
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<DT id="12"><A HREF="#lbAJ">COLOPHON</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:43 GMT, March 31, 2021
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</BODY>
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</HTML>
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