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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!-- Copyright 1997 The Open Group, All Rights Reserved --><title>freopen</title></head><body bgcolor=white><center><font size=2>The Single UNIX ® Specification, Version 2<br>Copyright © 1997 The Open Group</font></center><hr size=2 noshade><h4><a name = "tag_000_005_248"> </a>NAME</h4><blockquote>freopen - open a stream</blockquote><h4><a name = "tag_000_005_249"> </a>SYNOPSIS</h4><blockquote><pre><code>#include <<a href="stdio.h.html">stdio.h</a>>FILE *freopen(const char *<i>filename</i>, const char *<i>mode</i>, FILE *<i>stream</i>);</code></pre></blockquote><h4><a name = "tag_000_005_250"> </a>DESCRIPTION</h4><blockquote>The<i>freopen()</i>function first attempts to flush the stream and close any filedescriptor associated with<i>stream</i>.Failure to flush or close the file successfully is ignored.The error and end-of-file indicators for the stream are cleared.<p>The<i>freopen()</i>function opens the file whose pathname is the string pointed to by<i>filename</i>and associates the stream pointed to by<i>stream</i>with it.The<i>mode</i>argument is used just as in<i><a href="fopen.html">fopen()</a></i>.<p>The original stream is closed regardless ofwhether the subsequent open succeeds.<p>After a successful call to the<i>freopen()</i>function, the orientation of the stream is cleared and theassociated<b>mbstate_t</b>object is set to describe an initial conversion state.<p>The largest value that can be represented correctly in an object of type<b>off_t</b>will be established as the offset maximum in the open file description.</blockquote><h4><a name = "tag_000_005_251"> </a>RETURN VALUE</h4><blockquote>Upon successful completion,<i>freopen()</i>returns the value of<i>stream</i>.Otherwise a null pointer is returned and<i>errno</i>is set to indicate the error.</blockquote><h4><a name = "tag_000_005_252"> </a>ERRORS</h4><blockquote>The<i>freopen()</i>function will fail if:<dl compact><dt>[EACCES]<dd>Search permission is denied on a component of the path prefix,or the file exists and the permissions specified by<i>mode</i>are denied, or the file does not exist and write permission isdenied for the parent directory of the file to be created.<dt>[EINTR]<dd>A signal was caught during<i>freopen()</i>.<dt>[EISDIR]<dd>The named file is a directory and<i>mode</i>requires write access.<dt>[ELOOP]<dd>Too many symbolic links were encountered in resolving <i>path</i>.<dt>[EMFILE]<dd>{OPEN_MAX}file descriptors are currently open in the calling process.<dt>[ENAMETOOLONG]<dd>The length of the<i>filename</i>exceeds {PATH_MAX} or a pathname component is longer than {NAME_MAX}.<dt>[ENFILE]<dd>The maximum allowable number of files is currently open in thesystem.<dt>[ENOENT]<dd>A component of <i>filename</i> does not name an existing fileor <i>filename</i> is an empty string.<dt>[ENOSPC]<dd>The directory or file system that would contain thenew file cannot be expanded, the file does not exist, andit was to be created.<dt>[ENOTDIR]<dd>A component of the path prefix is not a directory.<dt>[ENXIO]<dd>The named file is a character special or block special file,and the device associated with this special file does not exist.<dt>[EOVERFLOW]<dd>The named file is a regular file and the size of the file cannot berepresented correctly in an object of type<b>off_t</b>.<dt>[EROFS]<dd>The named file resides on a read-only file system and<i>mode</i>requires write access.</dl><p>The<i>freopen()</i>function may fail if:<dl compact><dt>[EINVAL]<dd>The value of the<i>mode</i>argument is not valid.<dt>[ENAMETOOLONG]<dd>Pathname resolution of a symbolic link produced an intermediate result whoselength exceeds {PATH_MAX}.<dt>[ENOMEM]<dd>Insufficient storage space is available.<dt>[ENXIO]<dd>A request was made of a non-existent device, or the request wasoutside the capabilities of the device.<dt>[ETXTBSY]<dd>The file is a pure procedure (shared text) file that is beingexecuted and<i>mode</i>requires write access.</dl></blockquote><h4><a name = "tag_000_005_253"> </a>EXAMPLES</h4><blockquote>None.</blockquote><h4><a name = "tag_000_005_254"> </a>APPLICATION USAGE</h4><blockquote>The<i>freopen()</i>function is typically used to attach the preopened<i>streams</i>associated with<i><a href="stdin.html">stdin</a></i>,<i><a href="stdout.html">stdout</a></i>and<i><a href="stderr.html">stderr</a></i>to other files.</blockquote><h4><a name = "tag_000_005_255"> </a>FUTURE DIRECTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_000_005_256"> </a>SEE ALSO</h4><blockquote><i><a href="fclose.html">fclose()</a></i>,<i><a href="fopen.html">fopen()</a></i>,<i><a href="fdopen.html">fdopen()</a></i>,<i><a href="mbsinit.html">mbsinit()</a></i>,<i><a href="stdio.h.html"><stdio.h></a></i>.</blockquote><h4>DERIVATION</h4><blockquote>Derived from Issue 1 of the SVID.</blockquote><hr size=2 noshade><center><font size=2>UNIX ® is a registered Trademark of The Open Group.<br>Copyright © 1997 The Open Group<br> [ <a href="../index.html">Main Index</a> | <a href="../xshix.html">XSH</a> | <a href="../xcuix.html">XCU</a> | <a href="../xbdix.html">XBD</a> | <a href="../cursesix.html">XCURSES</a> | <a href="../xnsix.html">XNS</a> ]</font></center><hr size=2 noshade></body></html>⌨️ 快捷键说明
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