290 lines
5.8 KiB
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290 lines
5.8 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 OPENPTY</TITLE>
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</HEAD><BODY>
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<H1>OPENPTY</H1>
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Section: Linux Programmer's Manual (3)<BR>Updated: 2017-09-15<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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openpty, login_tty, forkpty - terminal utility functions
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<PRE>
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<B>#include <<A HREF="file:///usr/include/pty.h">pty.h</A>></B>
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<B>int openpty(int *</B><I>amaster</I><B>, int *</B><I>aslave</I><B>, char *</B><I>name</I><B>,</B>
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<B> const struct termios *</B><I>termp</I><B>,</B>
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<B> const struct winsize *</B><I>winp</I><B>);</B>
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<B>pid_t forkpty(int *</B><I>amaster</I><B>, char *</B><I>name</I><B>,</B>
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<B> const struct termios *</B><I>termp</I><B>,</B>
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<B> const struct winsize *</B><I>winp</I><B>);</B>
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<B>#include <<A HREF="file:///usr/include/utmp.h">utmp.h</A>></B>
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<B>int login_tty(int </B><I>fd</I><B>);</B>
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Link with <I>-lutil</I>.
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</PRE>
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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>openpty</B>()
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function finds an available pseudoterminal and returns file descriptors
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for the master and slave in
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<I>amaster</I>
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and
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<I>aslave</I>.
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If
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<I>name</I>
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is not NULL, the filename of the slave is returned in
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<I>name</I>.
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If
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<I>termp</I>
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is not NULL, the terminal parameters of the slave will be set to the
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values in
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<I>termp</I>.
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If
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<I>winp</I>
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is not NULL, the window size of the slave will be set to the values in
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<I>winp</I>.
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<P>
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The
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<B>login_tty</B>()
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function prepares for a login on the terminal
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<I>fd</I>
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(which may be a real terminal device, or the slave of a pseudoterminal as
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returned by
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<B>openpty</B>())
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by creating a new session, making
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<I>fd</I>
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the controlling terminal for the calling process, setting
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<I>fd</I>
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to be the standard input, output, and error streams of the current
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process, and closing
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<I>fd</I>.
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<P>
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The
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<B>forkpty</B>()
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function combines
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<B>openpty</B>(),
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<B><A HREF="/cgi-bin/man/man2html?2+fork">fork</A></B>(2),
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and
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<B>login_tty</B>()
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to create a new process operating in a pseudoterminal.
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The file
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descriptor of the master side of the pseudoterminal is returned in
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<I>amaster</I>.
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If
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<I>name</I>
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is not NULL, the buffer it points to is used to return the
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filename of the slave.
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The
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<I>termp</I>
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and
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<I>winp</I>
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arguments, if not NULL,
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will determine the terminal attributes and window size of the slave
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side of the pseudoterminal.
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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If a call to
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<B>openpty</B>(),
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<B>login_tty</B>(),
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or
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<B>forkpty</B>()
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is not successful, -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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Otherwise,
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<B>openpty</B>(),
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<B>login_tty</B>(),
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and the child process of
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<B>forkpty</B>()
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return 0, and the parent process of
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<B>forkpty</B>()
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returns the process ID of the child process.
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<A NAME="lbAF"> </A>
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<H2>ERRORS</H2>
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<B>openpty</B>()
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fails if:
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<DL COMPACT>
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<DT id="1"><B>ENOENT</B>
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<DD>
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There are no available terminals.
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</DL>
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<P>
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<B>login_tty</B>()
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fails if
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<B><A HREF="/cgi-bin/man/man2html?2+ioctl">ioctl</A></B>(2)
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fails to set
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<I>fd</I>
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to the controlling terminal of the calling process.
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<P>
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<B>forkpty</B>()
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fails if either
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<B>openpty</B>()
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or
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<B><A HREF="/cgi-bin/man/man2html?2+fork">fork</A></B>(2)
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fails.
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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>forkpty</B>(),
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<B>openpty</B>()
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</TD><TD>Thread safety</TD><TD>MT-Safe locale<BR></TD></TR>
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<TR VALIGN=top><TD>
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<B>login_tty</B>()
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</TD><TD>Thread safety</TD><TD>MT-Unsafe race:ttyname<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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These are BSD functions, present in glibc.
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They are not standardized in POSIX.
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<A NAME="lbAI"> </A>
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<H2>NOTES</H2>
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The
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<B>const</B>
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modifiers were added to the structure pointer arguments of
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<B>openpty</B>()
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and
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<B>forkpty</B>()
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in glibc 2.8.
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<P>
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In versions of glibc before 2.0.92,
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<B>openpty</B>()
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returns file descriptors for a BSD pseudoterminal pair;
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since glibc 2.0.92,
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it first attempts to open a UNIX 98 pseudoterminal pair,
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and falls back to opening a BSD pseudoterminal pair if that fails.
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<A NAME="lbAJ"> </A>
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<H2>BUGS</H2>
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Nobody knows how much space should be reserved for
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<I>name</I>.
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So, calling
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<B>openpty</B>()
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or
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<B>forkpty</B>()
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with non-NULL
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<I>name</I>
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may not be secure.
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<A NAME="lbAK"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?2+fork">fork</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?3+ttyname">ttyname</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?7+pty">pty</A></B>(7)
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<A NAME="lbAL"> </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="2"><A HREF="#lbAB">NAME</A><DD>
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<DT id="3"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="4"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="5"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="6"><A HREF="#lbAF">ERRORS</A><DD>
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<DT id="7"><A HREF="#lbAG">ATTRIBUTES</A><DD>
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<DT id="8"><A HREF="#lbAH">CONFORMING TO</A><DD>
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<DT id="9"><A HREF="#lbAI">NOTES</A><DD>
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<DT id="10"><A HREF="#lbAJ">BUGS</A><DD>
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<DT id="11"><A HREF="#lbAK">SEE ALSO</A><DD>
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<DT id="12"><A HREF="#lbAL">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: 00:05:49 GMT, March 31, 2021
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