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: open</title> 18 19<meta name="description" content="Debugging with GDB: open"> 20<meta name="keywords" content="Debugging with GDB: open"> 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="close.html#close" rel="next" title="close"> 30<link href="List-of-Supported-Calls.html#List-of-Supported-Calls" rel="previous" title="List of Supported Calls"> 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="open"></a> 65<div class="header"> 66<p> 67Next: <a href="close.html#close" accesskey="n" rel="next">close</a>, Up: <a href="List-of-Supported-Calls.html#List-of-Supported-Calls" accesskey="u" rel="up">List of Supported Calls</a> [<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="open-1"></a> 71<h4 class="unnumberedsubsubsec">open</h4> 72<a name="index-open_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 open(const char *pathname, int flags); 78int open(const char *pathname, int flags, mode_t mode); 79</pre></div> 80 81</dd> 82<dt>Request:</dt> 83<dd><p>‘<samp>Fopen,<var>pathptr</var>/<var>len</var>,<var>flags</var>,<var>mode</var></samp>’ 84</p> 85<p><var>flags</var> is the bitwise <code>OR</code> of the following values: 86</p> 87<dl compact="compact"> 88<dt><code>O_CREAT</code></dt> 89<dd><p>If the file does not exist it will be created. The host 90rules apply as far as file ownership and time stamps 91are concerned. 92</p> 93</dd> 94<dt><code>O_EXCL</code></dt> 95<dd><p>When used with <code>O_CREAT</code>, if the file already exists it is 96an error and open() fails. 97</p> 98</dd> 99<dt><code>O_TRUNC</code></dt> 100<dd><p>If the file already exists and the open mode allows 101writing (<code>O_RDWR</code> or <code>O_WRONLY</code> is given) it will be 102truncated to zero length. 103</p> 104</dd> 105<dt><code>O_APPEND</code></dt> 106<dd><p>The file is opened in append mode. 107</p> 108</dd> 109<dt><code>O_RDONLY</code></dt> 110<dd><p>The file is opened for reading only. 111</p> 112</dd> 113<dt><code>O_WRONLY</code></dt> 114<dd><p>The file is opened for writing only. 115</p> 116</dd> 117<dt><code>O_RDWR</code></dt> 118<dd><p>The file is opened for reading and writing. 119</p></dd> 120</dl> 121 122<p>Other bits are silently ignored. 123</p> 124 125<p><var>mode</var> is the bitwise <code>OR</code> of the following values: 126</p> 127<dl compact="compact"> 128<dt><code>S_IRUSR</code></dt> 129<dd><p>User has read permission. 130</p> 131</dd> 132<dt><code>S_IWUSR</code></dt> 133<dd><p>User has write permission. 134</p> 135</dd> 136<dt><code>S_IRGRP</code></dt> 137<dd><p>Group has read permission. 138</p> 139</dd> 140<dt><code>S_IWGRP</code></dt> 141<dd><p>Group has write permission. 142</p> 143</dd> 144<dt><code>S_IROTH</code></dt> 145<dd><p>Others have read permission. 146</p> 147</dd> 148<dt><code>S_IWOTH</code></dt> 149<dd><p>Others have write permission. 150</p></dd> 151</dl> 152 153<p>Other bits are silently ignored. 154</p> 155 156</dd> 157<dt>Return value:</dt> 158<dd><p><code>open</code> returns the new file descriptor or -1 if an error 159occurred. 160</p> 161</dd> 162<dt>Errors:</dt> 163<dd> 164<dl compact="compact"> 165<dt><code>EEXIST</code></dt> 166<dd><p><var>pathname</var> already exists and <code>O_CREAT</code> and <code>O_EXCL</code> were used. 167</p> 168</dd> 169<dt><code>EISDIR</code></dt> 170<dd><p><var>pathname</var> refers to a directory. 171</p> 172</dd> 173<dt><code>EACCES</code></dt> 174<dd><p>The requested access is not allowed. 175</p> 176</dd> 177<dt><code>ENAMETOOLONG</code></dt> 178<dd><p><var>pathname</var> was too long. 179</p> 180</dd> 181<dt><code>ENOENT</code></dt> 182<dd><p>A directory component in <var>pathname</var> does not exist. 183</p> 184</dd> 185<dt><code>ENODEV</code></dt> 186<dd><p><var>pathname</var> refers to a device, pipe, named pipe or socket. 187</p> 188</dd> 189<dt><code>EROFS</code></dt> 190<dd><p><var>pathname</var> refers to a file on a read-only filesystem and 191write access was requested. 192</p> 193</dd> 194<dt><code>EFAULT</code></dt> 195<dd><p><var>pathname</var> is an invalid pointer value. 196</p> 197</dd> 198<dt><code>ENOSPC</code></dt> 199<dd><p>No space on device to create the file. 200</p> 201</dd> 202<dt><code>EMFILE</code></dt> 203<dd><p>The process already has the maximum number of files open. 204</p> 205</dd> 206<dt><code>ENFILE</code></dt> 207<dd><p>The limit on the total number of files open on the system 208has been reached. 209</p> 210</dd> 211<dt><code>EINTR</code></dt> 212<dd><p>The call was interrupted by the user. 213</p></dd> 214</dl> 215 216</dd> 217</dl> 218 219<hr> 220<div class="header"> 221<p> 222Next: <a href="close.html#close" accesskey="n" rel="next">close</a>, Up: <a href="List-of-Supported-Calls.html#List-of-Supported-Calls" accesskey="u" rel="up">List of Supported Calls</a> [<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> 223</div> 224 225 226 227</body> 228</html> 229