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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>Chapter 2. Managing procfs entries</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="Linux Kernel Procfs Guide" /><link rel="up" href="index.html" title="Linux Kernel Procfs Guide" /><link rel="prev" href="ch01.html" title="Chapter 1. Introduction" /><link rel="next" href="ch02s02.html" title="Creating a symlink" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 2. Managing procfs entries</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch01.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ch02s02.html">Next</a></td></tr></table><hr /></div><div class="chapter" title="Chapter 2. Managing procfs entries"><div class="titlepage"><div><div><h2 class="title"><a id="managing"></a>Chapter 2. Managing procfs entries</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="ch02.html#regularfile">Creating a regular file</a></span></dt><dt><span class="sect1"><a href="ch02s02.html">Creating a symlink</a></span></dt><dt><span class="sect1"><a href="ch02s03.html">Creating a directory</a></span></dt><dt><span class="sect1"><a href="ch02s04.html">Removing an entry</a></span></dt></dl></div><p>
This chapter describes the functions that various kernel
components use to populate the procfs with files, symlinks,
device nodes, and directories.
</p><p>
A minor note before we start: if you want to use any of the
procfs functions, be sure to include the correct header file!
This should be one of the first lines in your code:
</p><pre class="programlisting">
#include <linux/proc_fs.h>
</pre><div class="sect1" title="Creating a regular file"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="regularfile"></a>Creating a regular file</h2></div></div></div><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">struct proc_dir_entry* <b class="fsfunc">create_proc_entry</b>(</code></td><td>const char* <var class="pdparam">name</var>, </td></tr><tr><td> </td><td>mode_t <var class="pdparam">mode</var>, </td></tr><tr><td> </td><td>struct proc_dir_entry* <var class="pdparam">parent</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div><p>
This function creates a regular file with the name
<em class="parameter"><code>name</code></em>, file mode
<em class="parameter"><code>mode</code></em> in the directory
<em class="parameter"><code>parent</code></em>. To create a file in the root of
the procfs, use <code class="constant">NULL</code> as
<em class="parameter"><code>parent</code></em> parameter. When successful, the
function will return a pointer to the freshly created
<span class="structname">struct proc_dir_entry</span>; otherwise it
will return <code class="constant">NULL</code>. <a class="xref" href="ch03.html" title="Chapter 3. Communicating with userland">Chapter 3, <i>Communicating with userland</i></a> describes how to do something useful with
regular files.
</p><p>
Note that it is specifically supported that you can pass a
path that spans multiple directories. For example
<code class="function">create_proc_entry</code>(<em class="parameter"><code>"drivers/via0/info"</code></em>)
will create the <code class="filename">via0</code>
directory if necessary, with standard
<code class="constant">0755</code> permissions.
</p><p>
If you only want to be able to read the file, the function
<code class="function">create_proc_read_entry</code> described in <a class="xref" href="ch04.html#convenience" title="Convenience functions">the section called “Convenience functions”</a> may be used to create and initialise
the procfs entry in one single call.
</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch01.html">Prev</a> </td><td width="20%" align="center"> </td><td width="40%" align="right"> <a accesskey="n" href="ch02s02.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 1. Introduction </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Creating a symlink</td></tr></table></div></body></html>
