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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) 2001-2003 The Open Group, All Rights Reserved --><title>tty</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="tty"></a> <a name="tag_04_149"></a><!-- tty --> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2003 Edition<br>Copyright © 2001-2003 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h4><a name="tag_04_149_01"></a>NAME</h4><blockquote>tty - return user's terminal name</blockquote><h4><a name="tag_04_149_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><p><code><tt>tty</tt></code></p></blockquote><h4><a name="tag_04_149_03"></a>DESCRIPTION</h4><blockquote><p>The <i>tty</i> utility shall write to the standard output the name of the terminal that is open as standard input. The name thatis used shall be equivalent to the string that would be returned by the <a href="../functions/ttyname.html"><i>ttyname</i>()</a>function defined in the System Interfaces volume of IEEE Std 1003.1-2001.</p></blockquote><h4><a name="tag_04_149_04"></a>OPTIONS</h4><blockquote><p>The <i>tty</i> utility shall conform to the Base Definitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap12.html#tag_12_02">Section 12.2, Utility Syntax Guidelines</a>.</p></blockquote><h4><a name="tag_04_149_05"></a>OPERANDS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_149_06"></a>STDIN</h4><blockquote><p>While no input is read from standard input, standard input shall be examined to determine whether or not it is a terminal, and,if so, to determine the name of the terminal.</p></blockquote><h4><a name="tag_04_149_07"></a>INPUT FILES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_149_08"></a>ENVIRONMENT VARIABLES</h4><blockquote><p>The following environment variables shall affect the execution of <i>tty</i>:</p><dl compact><dt><i>LANG</i></dt><dd>Provide a default value for the internationalization variables that are unset or null. (See the Base Definitions volume ofIEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap08.html#tag_08_02">Section 8.2, Internationalization Variables</a> forthe precedence of internationalization variables used to determine the values of locale categories.)</dd><dt><i>LC_ALL</i></dt><dd>If set to a non-empty string value, override the values of all the other internationalization variables.</dd><dt><i>LC_CTYPE</i></dt><dd>Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte asopposed to multi-byte characters in arguments).</dd><dt><i>LC_MESSAGES</i></dt><dd>Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error andinformative messages written to standard output.</dd><dt><i>NLSPATH</i></dt><dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">Determine the location of message catalogs for the processing of <i>LC_MESSAGES .</i> <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd></dl></blockquote><h4><a name="tag_04_149_09"></a>ASYNCHRONOUS EVENTS</h4><blockquote><p>Default.</p></blockquote><h4><a name="tag_04_149_10"></a>STDOUT</h4><blockquote><p>If standard input is a terminal device, a pathname of the terminal as specified by the <a href="../functions/ttyname.html"><i>ttyname</i>()</a> function defined in the System Interfaces volume of IEEE Std 1003.1-2001shall be written in the following format:</p><pre><tt>"%s\n", <</tt><i>terminal name</i><tt>></tt></pre><p>Otherwise, a message shall be written indicating that standard input is not connected to a terminal. In the POSIX locale, the<i>tty</i> utility shall use the format:</p><pre><tt>"not a tty\n"</tt></pre></blockquote><h4><a name="tag_04_149_11"></a>STDERR</h4><blockquote><p>The standard error shall be used only for diagnostic messages.</p></blockquote><h4><a name="tag_04_149_12"></a>OUTPUT FILES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_149_13"></a>EXTENDED DESCRIPTION</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_149_14"></a>EXIT STATUS</h4><blockquote><p>The following exit values shall be returned:</p><dl compact><dt> 0</dt><dd>Standard input is a terminal.</dd><dt> 1</dt><dd>Standard input is not a terminal.</dd><dt>>1</dt><dd>An error occurred.</dd></dl></blockquote><h4><a name="tag_04_149_15"></a>CONSEQUENCES OF ERRORS</h4><blockquote><p>Default.</p></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_04_149_16"></a>APPLICATION USAGE</h4><blockquote><p>This utility checks the status of the file open as standard input against that of an implementation-defined set of files. It ispossible that no match can be found, or that the match found need not be the same file as that which was opened for standard input(although they are the same device).</p></blockquote><h4><a name="tag_04_149_17"></a>EXAMPLES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_149_18"></a>RATIONALE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_149_19"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_149_20"></a>SEE ALSO</h4><blockquote><p>The System Interfaces volume of IEEE Std 1003.1-2001, <a href="../functions/isatty.html"><i>isatty</i>()</a>, <a href="../functions/ttyname.html"><i>ttyname</i>()</a></p></blockquote><h4><a name="tag_04_149_21"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 2.</p></blockquote><h4><a name="tag_04_149_22"></a>Issue 5</h4><blockquote><p>The SYNOPSIS is changed to indicate two forms of the command, with the second form marked as obsolete. This is a clarificationand does not change the functionality published in previous issues.</p></blockquote><h4><a name="tag_04_149_23"></a>Issue 6</h4><blockquote><p>The obsolescent <b>-s</b> option is removed.</p></blockquote><div class="box"><em>End of informative text.</em></div><hr><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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