man-pages/man3/posix_openpt.3.html
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<H1>POSIX_OPENPT</H1>
Section: Linux Programmer's Manual (3)<BR>Updated: 2017-09-15<BR><A HREF="#index">Index</A>
<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
<A NAME="lbAB">&nbsp;</A>
<H2>NAME</H2>
posix_openpt - open a pseudoterminal device
<A NAME="lbAC">&nbsp;</A>
<H2>SYNOPSIS</H2>
<PRE>
<B>#include &lt;<A HREF="file:///usr/include/stdlib.h">stdlib.h</A>&gt;</B>
<B>#include &lt;<A HREF="file:///usr/include/fcntl.h">fcntl.h</A>&gt;</B>
<B>int posix_openpt(int </B><I>flags</I><B>);</B>
</PRE>
<P>
Feature Test Macro Requirements for glibc (see
<B><A HREF="/cgi-bin/man/man2html?7+feature_test_macros">feature_test_macros</A></B>(7)):
<P>
<B>posix_openpt</B>():
_XOPEN_SOURCE&nbsp;&gt;=&nbsp;600
<A NAME="lbAD">&nbsp;</A>
<H2>DESCRIPTION</H2>
The
<B>posix_openpt</B>()
function opens an unused pseudoterminal master device, returning a
file descriptor that can be used to refer to that device.
<P>
The
<I>flags</I>
argument is a bit mask that ORs together zero or more of
the following flags:
<DL COMPACT>
<DT id="1"><B>O_RDWR</B>
<DD>
Open the device for both reading and writing.
It is usual to specify this flag.
<DT id="2"><B>O_NOCTTY</B>
<DD>
Do not make this device the controlling terminal for the process.
</DL>
<A NAME="lbAE">&nbsp;</A>
<H2>RETURN VALUE</H2>
On success,
<B>posix_openpt</B>()
returns a nonnegative file descriptor which is the lowest
numbered unused file descriptor.
On failure, -1 is returned, and
<I>errno</I>
is set to indicate the error.
<A NAME="lbAF">&nbsp;</A>
<H2>ERRORS</H2>
See
<B><A HREF="/cgi-bin/man/man2html?2+open">open</A></B>(2).
<A NAME="lbAG">&nbsp;</A>
<H2>VERSIONS</H2>
Glibc support for
<B>posix_openpt</B>()
has been provided since version 2.2.1.
<A NAME="lbAH">&nbsp;</A>
<H2>ATTRIBUTES</H2>
For an explanation of the terms used in this section, see
<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
<TABLE BORDER>
<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
<TR VALIGN=top><TD>
<B>posix_openpt</B>()
</TD><TD>Thread safety</TD><TD>MT-Safe<BR></TD></TR>
</TABLE>
<A NAME="lbAI">&nbsp;</A>
<H2>CONFORMING TO</H2>
POSIX.1-2001, POSIX.1-2008.
<P>
<B>posix_openpt</B>()
is part of the UNIX 98 pseudoterminal support (see
<B><A HREF="/cgi-bin/man/man2html?4+pts">pts</A></B>(4)).
<A NAME="lbAJ">&nbsp;</A>
<H2>NOTES</H2>
Some older UNIX implementations that support System V
(aka UNIX 98) pseudoterminals don't have this function, but it
is easy to implement:
<P>
int
posix_openpt(int flags)
{
<BR>&nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;open(&quot;/dev/ptmx&quot;,&nbsp;flags);
}
<P>
Calling
<B>posix_openpt</B>()
creates a pathname for the corresponding pseudoterminal slave device.
The pathname of the slave device can be obtained using
<B><A HREF="/cgi-bin/man/man2html?3+ptsname">ptsname</A></B>(3).
The slave device pathname exists only as long as the master device is open.
<A NAME="lbAK">&nbsp;</A>
<H2>SEE ALSO</H2>
<B><A HREF="/cgi-bin/man/man2html?2+open">open</A></B>(2),
<B><A HREF="/cgi-bin/man/man2html?3+getpt">getpt</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+grantpt">grantpt</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+ptsname">ptsname</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+unlockpt">unlockpt</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?4+pts">pts</A></B>(4),
<B><A HREF="/cgi-bin/man/man2html?7+pty">pty</A></B>(7)
<A NAME="lbAL">&nbsp;</A>
<H2>COLOPHON</H2>
This page is part of release 5.05 of the Linux
<I>man-pages</I>
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
<P>
<HR>
<A NAME="index">&nbsp;</A><H2>Index</H2>
<DL>
<DT id="3"><A HREF="#lbAB">NAME</A><DD>
<DT id="4"><A HREF="#lbAC">SYNOPSIS</A><DD>
<DT id="5"><A HREF="#lbAD">DESCRIPTION</A><DD>
<DT id="6"><A HREF="#lbAE">RETURN VALUE</A><DD>
<DT id="7"><A HREF="#lbAF">ERRORS</A><DD>
<DT id="8"><A HREF="#lbAG">VERSIONS</A><DD>
<DT id="9"><A HREF="#lbAH">ATTRIBUTES</A><DD>
<DT id="10"><A HREF="#lbAI">CONFORMING TO</A><DD>
<DT id="11"><A HREF="#lbAJ">NOTES</A><DD>
<DT id="12"><A HREF="#lbAK">SEE ALSO</A><DD>
<DT id="13"><A HREF="#lbAL">COLOPHON</A><DD>
</DL>
<HR>
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