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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta name="generator" content="HTML Tidy, see www.w3.org"><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 --><!-- Copyright (c) 2001-2003 The Open Group, All Rights Reserved --><title>closelog</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="closelog"></a> <a name="tag_03_82"></a><!-- closelog --> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2003 Edition<br>Copyright © 2001-2003 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h4><a name="tag_03_82_01"></a>NAME</h4><blockquote>closelog, openlog, setlogmask, syslog - control system log</blockquote><h4><a name="tag_03_82_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><div class="box"><code><tt><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> #include <<a href="../basedefs/syslog.h.html">syslog.h</a>><br><br> void closelog(void);<br> void openlog(const char *</tt><i>ident</i><tt>, int</tt> <i>logopt</i><tt>, int</tt> <i>facility</i><tt>);<br> int setlogmask(int</tt> <i>maskpri</i><tt>);<br> void syslog(int</tt> <i>priority</i><tt>, const char *</tt><i>message</i><tt>, ... /*</tt> <i>arguments</i> <tt>*/); <img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div><tt><br></tt></blockquote><h4><a name="tag_03_82_03"></a>DESCRIPTION</h4><blockquote><p>The <i>syslog</i>() function shall send a message to an implementation-defined logging facility, which may log it in animplementation-defined system log, write it to the system console, forward it to a list of users, or forward it to the loggingfacility on another host over the network. The logged message shall include a message header and a message body. The message headercontains at least a timestamp and a tag string.</p><p>The message body is generated from the <i>message</i> and following arguments in the same manner as if these were arguments to<a href="../functions/printf.html"><i>printf</i>()</a>, except that the additional conversion specification <tt>%m</tt> shall berecognized; it shall convert no arguments, shall cause the output of the error message string associated with the value of<i>errno</i> on entry to <i>syslog</i>(), and may be mixed with argument specifications of the <tt>"%</tt><i>n</i><tt>$"</tt> form.If a complete conversion specification with the <tt>m</tt> conversion specifier character is not just <tt>%m</tt> , the behavior isundefined. A trailing <newline> may be added if needed.</p><p>Values of the <i>priority</i> argument are formed by OR'ing together a severity-level value and an optional facility value. Ifno facility value is specified, the current default facility value is used.</p><p>Possible values of severity level include:</p><dl compact><dt>LOG_EMERG</dt><dd>A panic condition.</dd><dt>LOG_ALERT</dt><dd>A condition that should be corrected immediately, such as a corrupted system database.</dd><dt>LOG_CRIT</dt><dd>Critical conditions, such as hard device errors.</dd><dt>LOG_ERR</dt><dd>Errors.</dd><dt>LOG_WARNING</dt><dd><br>Warning messages.</dd><dt>LOG_NOTICE</dt><dd>Conditions that are not error conditions, but that may require special handling.</dd><dt>LOG_INFO</dt><dd>Informational messages.</dd><dt>LOG_DEBUG</dt><dd>Messages that contain information normally of use only when debugging a program.</dd></dl><p>The facility indicates the application or system component generating the message. Possible facility values include:</p><dl compact><dt>LOG_USER</dt><dd>Messages generated by arbitrary processes. This is the default facility identifier if none is specified.</dd><dt>LOG_LOCAL0</dt><dd>Reserved for local use.</dd><dt>LOG_LOCAL1</dt><dd>Reserved for local use.</dd><dt>LOG_LOCAL2</dt><dd>Reserved for local use.</dd><dt>LOG_LOCAL3</dt><dd>Reserved for local use.</dd><dt>LOG_LOCAL4</dt><dd>Reserved for local use.</dd><dt>LOG_LOCAL5</dt><dd>Reserved for local use.</dd><dt>LOG_LOCAL6</dt><dd>Reserved for local use.</dd><dt>LOG_LOCAL7</dt><dd>Reserved for local use.</dd></dl><p>The <i>openlog</i>() function shall set process attributes that affect subsequent calls to <i>syslog</i>(). The <i>ident</i>argument is a string that is prepended to every message. The <i>logopt</i> argument indicates logging options. Values for<i>logopt</i> are constructed by a bitwise-inclusive OR of zero or more of the following:</p><dl compact><dt>LOG_PID</dt><dd>Log the process ID with each message. This is useful for identifying specific processes.</dd><dt>LOG_CONS</dt><dd>Write messages to the system console if they cannot be sent to the logging facility. The <i>syslog</i>() function ensures thatthe process does not acquire the console as a controlling terminal in the process of writing the message.</dd><dt>LOG_NDELAY</dt><dd>Open the connection to the logging facility immediately. Normally the open is delayed until the first message is logged. Thisis useful for programs that need to manage the order in which file descriptors are allocated.</dd><dt>LOG_ODELAY</dt><dd>Delay open until <i>syslog</i>() is called.</dd><dt>LOG_NOWAIT</dt><dd>Do not wait for child processes that may have been created during the course of logging the message. This option should be usedby processes that enable notification of child termination using SIGCHLD, since <i>syslog</i>() may otherwise block waiting for achild whose exit status has already been collected.</dd></dl><p>The <i>facility</i> argument encodes a default facility to be assigned to all messages that do not have an explicit facilityalready encoded. The initial default facility is LOG_USER.</p><p>The <i>openlog</i>() and <i>syslog</i>() functions may allocate a file descriptor. It is not necessary to call <i>openlog</i>()prior to calling <i>syslog</i>().</p><p>The <i>closelog</i>() function shall close any open file descriptors allocated by previous calls to <i>openlog</i>() or<i>syslog</i>().</p><p>The <i>setlogmask</i>() function shall set the log priority mask for the current process to <i>maskpri</i> and return theprevious mask. If the <i>maskpri</i> argument is 0, the current log mask is not modified. Calls by the current process to<i>syslog</i>() with a priority not set in <i>maskpri</i> shall be rejected. The default log mask allows all priorities to belogged. A call to <i>openlog</i>() is not required prior to calling <i>setlogmask</i>().</p><p>Symbolic constants for use as values of the <i>logopt</i>, <i>facility</i>, <i>priority</i>, and <i>maskpri</i> arguments aredefined in the <a href="../basedefs/syslog.h.html"><i><syslog.h></i></a> header.</p></blockquote><h4><a name="tag_03_82_04"></a>RETURN VALUE</h4><blockquote><p>The <i>setlogmask</i>() function shall return the previous log priority mask. The <i>closelog</i>(), <i>openlog</i>(), and<i>syslog</i>() functions shall not return a value.</p></blockquote><h4><a name="tag_03_82_05"></a>ERRORS</h4><blockquote><p>No errors are defined.</p></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_03_82_06"></a>EXAMPLES</h4><blockquote><h5><a name="tag_03_82_06_01"></a>Using openlog()</h5><p>The following example causes subsequent calls to <i>syslog</i>() to log the process ID with each message, and to write messagesto the system console if they cannot be sent to the logging facility.</p><pre><tt>#include <syslog.h><br>char *ident = "Process demo";int logopt = LOG_PID | LOG_CONS;int facility = LOG_USER;...openlog(ident, logopt, facility);</tt></pre><h5><a name="tag_03_82_06_02"></a>Using setlogmask()</h5><p>The following example causes subsequent calls to <i>syslog</i>() to accept error messages, and to reject all other messages.</p><pre><tt>#include <syslog.h><br>int result;int mask = LOG_MASK (LOG_ERR);...result = setlogmask(mask);</tt></pre><h5><a name="tag_03_82_06_03"></a>Using syslog</h5><p>The following example sends the message <tt>"This is a message"</tt> to the default logging facility, marking the message as anerror message generated by random processes.</p><pre><tt>#include <syslog.h><br>char *message = "This is a message";int priority = LOG_ERR | LOG_USER;...syslog(priority, message);</tt></pre></blockquote><h4><a name="tag_03_82_07"></a>APPLICATION USAGE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_82_08"></a>RATIONALE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_82_09"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_82_10"></a>SEE ALSO</h4><blockquote><p><a href="printf.html"><i>printf</i>()</a> , the Base Definitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/syslog.h.html"><i><syslog.h></i></a></p></blockquote><h4><a name="tag_03_82_11"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 4, Version 2.</p></blockquote><h4><a name="tag_03_82_12"></a>Issue 5</h4><blockquote><p>Moved from X/OPEN UNIX extension to BASE.</p></blockquote><h4><a name="tag_03_82_13"></a>Issue 6</h4><blockquote><p>IEEE Std 1003.1-2001/Cor 1-2002, item XSH/TC1/D6/13 is applied, correcting the EXAMPLES section.</p></blockquote><div class="box"><em>End of informative text.</em></div><hr><hr size="2" noshade><center><font size="2"><!--footer start-->UNIX ® is a registered Trademark of The Open Group.<br>POSIX ® is a registered Trademark of The IEEE.<br>[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href="../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>]</font></center><!--footer end--><hr size="2" noshade></body></html>⌨️ 快捷键说明
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