1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
2<html>
3<!-- Copyright (C) 1988-2021 Free Software Foundation, Inc.
4
5Permission is granted to copy, distribute and/or modify this document
6under the terms of the GNU Free Documentation License, Version 1.3 or
7any later version published by the Free Software Foundation; with the
8Invariant Sections being "Free Software" and "Free Software Needs
9Free Documentation", with the Front-Cover Texts being "A GNU Manual,"
10and with the Back-Cover Texts as in (a) below.
11
12(a) The FSF's Back-Cover Text is: "You are free to copy and modify
13this GNU Manual.  Buying copies from GNU Press supports the FSF in
14developing GNU and promoting software freedom." -->
15<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ -->
16<head>
17<title>Debugging with GDB: isatty</title>
18
19<meta name="description" content="Debugging with GDB: isatty">
20<meta name="keywords" content="Debugging with GDB: isatty">
21<meta name="resource-type" content="document">
22<meta name="distribution" content="global">
23<meta name="Generator" content="makeinfo">
24<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
25<link href="index.html#Top" rel="start" title="Top">
26<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
27<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
28<link href="List-of-Supported-Calls.html#List-of-Supported-Calls" rel="up" title="List of Supported Calls">
29<link href="system.html#system" rel="next" title="system">
30<link href="gettimeofday.html#gettimeofday" rel="previous" title="gettimeofday">
31<style type="text/css">
32<!--
33a.summary-letter {text-decoration: none}
34blockquote.smallquotation {font-size: smaller}
35div.display {margin-left: 3.2em}
36div.example {margin-left: 3.2em}
37div.indentedblock {margin-left: 3.2em}
38div.lisp {margin-left: 3.2em}
39div.smalldisplay {margin-left: 3.2em}
40div.smallexample {margin-left: 3.2em}
41div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
42div.smalllisp {margin-left: 3.2em}
43kbd {font-style:oblique}
44pre.display {font-family: inherit}
45pre.format {font-family: inherit}
46pre.menu-comment {font-family: serif}
47pre.menu-preformatted {font-family: serif}
48pre.smalldisplay {font-family: inherit; font-size: smaller}
49pre.smallexample {font-size: smaller}
50pre.smallformat {font-family: inherit; font-size: smaller}
51pre.smalllisp {font-size: smaller}
52span.nocodebreak {white-space:nowrap}
53span.nolinebreak {white-space:nowrap}
54span.roman {font-family:serif; font-weight:normal}
55span.sansserif {font-family:sans-serif; font-weight:normal}
56ul.no-bullet {list-style: none}
57-->
58</style>
59
60
61</head>
62
63<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
64<a name="isatty"></a>
65<div class="header">
66<p>
67Next: <a href="system.html#system" accesskey="n" rel="next">system</a>, Previous: <a href="gettimeofday.html#gettimeofday" accesskey="p" rel="previous">gettimeofday</a>, Up: <a href="List-of-Supported-Calls.html#List-of-Supported-Calls" accesskey="u" rel="up">List of Supported Calls</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
68</div>
69<hr>
70<a name="isatty-1"></a>
71<h4 class="unnumberedsubsubsec">isatty</h4>
72<a name="index-isatty_002c-file_002di_002fo-system-call"></a>
73
74<dl compact="compact">
75<dt>Synopsis:</dt>
76<dd><div class="smallexample">
77<pre class="smallexample">int isatty(int fd);
78</pre></div>
79
80</dd>
81<dt>Request:</dt>
82<dd><p>&lsquo;<samp>Fisatty,<var>fd</var></samp>&rsquo;
83</p>
84</dd>
85<dt>Return value:</dt>
86<dd><p>Returns 1 if <var>fd</var> refers to the <small>GDB</small> console, 0 otherwise.
87</p>
88</dd>
89<dt>Errors:</dt>
90<dd>
91<dl compact="compact">
92<dt><code>EINTR</code></dt>
93<dd><p>The call was interrupted by the user.
94</p></dd>
95</dl>
96
97</dd>
98</dl>
99
100<p>Note that the <code>isatty</code> call is treated as a special case: it returns
1011 to the target if the file descriptor is attached
102to the <small>GDB</small> console, 0 otherwise.  Implementing through system calls
103would require implementing <code>ioctl</code> and would be more complex than
104needed.
105</p>
106
107
108
109
110</body>
111</html>
112