<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>Run-time error information</title> <link rel="stylesheet" href="gettingStarted.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> <link rel="start" href="index.html" title="Berkeley DB Installation and Build Guide" /> <link rel="up" href="debug.html" title="Chapter 3. Debugging Applications" /> <link rel="prev" href="debug_compile.html" title="Compile-time configuration" /> <link rel="next" href="debug_printlog.html" title="Reviewing Berkeley DB log files" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">Run-time error information</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="debug_compile.html">Prev</a> </td> <th width="60%" align="center">Chapter 3. Debugging Applications </th> <td width="20%" align="right"> <a accesskey="n" href="debug_printlog.html">Next</a></td> </tr> </table> <hr /> </div> <div class="sect1" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="debug_runtime"></a>Run-time error information</h2> </div> </div> </div> <p>Normally, when an error occurs in the Berkeley DB library, an integer value (either a Berkeley DB specific value or a system <code class="literal">errno</code> value) is returned by Berkeley DB. In some cases, however, this value may be insufficient to completely describe the cause of the error, especially during initial application debugging.</p> <p>Most Berkeley DB errors will result in additional information being written to a standard file descriptor or output stream. Additionally, Berkeley DB can be configured to pass these verbose error messages to an application function. There are four methods intended to provide applications with additional error information: <a href="../api_reference/C/envset_errcall.html" class="olink">DB_ENV->set_errcall()</a>, <a href="../api_reference/C/envset_errfile.html" class="olink">DB_ENV->set_errfile()</a>, <a href="../api_reference/C/envset_errpfx.html" class="olink">DB_ENV->set_errpfx()</a> and <a href="../api_reference/C/envset_verbose.html" class="olink">DB_ENV->set_verbose()</a>.</p> <p>The Berkeley DB error-reporting facilities do not slow performance or significantly increase application size, and may be run during normal operation as well as during debugging. Where possible, we recommend these options always be configured and the output saved in the filesystem. We have found that this often saves time when debugging installation or other system-integration problems.</p> <p>In addition, there are three methods to assist applications in displaying their own error messages: <a href="../api_reference/C/envstrerror.html" class="olink">db_strerror()</a>, <a href="../api_reference/C/enverr.html" class="olink">DB_ENV->err()</a>, and <code class="methodname">DB_ENV->errx()</code>. The first is a superset of the ANSI C strerror function, and returns a descriptive string for any error return from the Berkeley DB library. The <a href="../api_reference/C/enverr.html" class="olink">DB_ENV->err()</a> and <code class="methodname">DB_ENV->errx()</code> methods use the error message configuration options described previously to format and display error messages to appropriate output devices.</p> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="debug_compile.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="debug.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="debug_printlog.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">Compile-time configuration </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> Reviewing Berkeley DB log files</td> </tr> </table> </div> </body> </html>