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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta name="generator" content="HTML Tidy, see www.w3.org"><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 --><!-- Copyright (c) 2001-2004 IEEE and The Open Group, All Rights Reserved --><title>tcflow</title></head><body bgcolor="white"><basefont size="3"> <a name="tcflow"></a> <a name="tag_03_762"></a><!-- tcflow --> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2004 Edition<br>Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h4><a name="tag_03_762_01"></a>NAME</h4><blockquote>tcflow - suspend or restart the transmission or reception of data</blockquote><h4><a name="tag_03_762_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><p><code><tt>#include <<a href="../basedefs/termios.h.html">termios.h</a>><br><br> int tcflow(int</tt> <i>fildes</i><tt>, int</tt> <i>action</i><tt>);<br></tt></code></p></blockquote><h4><a name="tag_03_762_03"></a>DESCRIPTION</h4><blockquote><p>The <i>tcflow</i>() function shall suspend or restart transmission or reception of data on the object referred to by<i>fildes</i>, depending on the value of <i>action</i>. The <i>fildes</i> argument is an open file descriptor associated with aterminal.</p><ul><li><p>If <i>action</i> is TCOOFF, output shall be suspended.</p></li><li><p>If <i>action</i> is TCOON, suspended output shall be restarted.</p></li><li><p>If <i>action</i> is TCIOFF, the system shall transmit a STOP character, which is intended to cause the terminal device to stoptransmitting data to the system.</p></li><li><p>If <i>action</i> is TCION, the system shall transmit a START character, which is intended to cause the terminal device to starttransmitting data to the system.</p></li></ul><p>The default on the opening of a terminal file is that neither its input nor its output are suspended.</p><p>Attempts to use <i>tcflow</i>() from a process which is a member of a background process group on a <i>fildes</i> associatedwith its controlling terminal, shall cause the process group to be sent a SIGTTOU signal. If the calling process is blocking orignoring SIGTTOU signals, the process shall be allowed to perform the operation, and no signal is sent.</p></blockquote><h4><a name="tag_03_762_04"></a>RETURN VALUE</h4><blockquote><p>Upon successful completion, 0 shall be returned. Otherwise, -1 shall be returned and <i>errno</i> set to indicate the error.</p></blockquote><h4><a name="tag_03_762_05"></a>ERRORS</h4><blockquote><p>The <i>tcflow</i>() function shall fail if:</p><dl compact><dt>[EBADF]</dt><dd>The <i>fildes</i> argument is not a valid file descriptor.</dd><dt>[EINVAL]</dt><dd>The <i>action</i> argument is not a supported value.</dd><dt>[ENOTTY]</dt><dd>The file associated with <i>fildes</i> is not a terminal.</dd></dl><p>The <i>tcflow</i>() function may fail if:</p><dl compact><dt>[EIO]</dt><dd>The process group of the writing process is orphaned, and the writing process is not ignoring or blocking SIGTTOU.</dd></dl></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_03_762_06"></a>EXAMPLES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_762_07"></a>APPLICATION USAGE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_762_08"></a>RATIONALE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_762_09"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_762_10"></a>SEE ALSO</h4><blockquote><p><a href="tcsendbreak.html"><i>tcsendbreak</i>()</a>, the Base Definitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap11.html#tag_11">Chapter 11, General Terminal Interface</a>, <a href="../basedefs/termios.h.html"><i><termios.h></i></a>, <a href="../basedefs/unistd.h.html"><i><unistd.h></i></a></p></blockquote><h4><a name="tag_03_762_11"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 3. Included for alignment with the POSIX.1-1988 standard.</p></blockquote><h4><a name="tag_03_762_12"></a>Issue 6</h4><blockquote><p>The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:</p><ul><li><p>The [EIO] error is added.</p></li></ul></blockquote><div class="box"><em>End of informative text.</em></div><hr size="2" noshade><center><font size="2"><!--footer start-->UNIX ® is a registered Trademark of The Open Group.<br>POSIX ® is a registered Trademark of The IEEE.<br>[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href="../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>]</font></center><!--footer end--><hr size="2" noshade></body></html>⌨️ 快捷键说明
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