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| <h4 class="subsection">18.2.2 syslog, vsyslog</h4> |
| |
| <p>The symbols referred to in this section are declared in the file |
| <samp><span class="file">syslog.h</span></samp>. |
| |
| <!-- syslog() is implemented as a call to vsyslog(). --> |
| <!-- syslog.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Function: void <b>syslog</b> (<var>int facility_priority, char *format, ...</var>)<var><a name="index-syslog-2035"></a></var><br> |
| <blockquote> |
| <p><code>syslog</code> submits a message to the Syslog facility. It does this by |
| writing to the Unix domain socket <code>/dev/log</code>. |
| |
| <p><code>syslog</code> submits the message with the facility and priority indicated |
| by <var>facility_priority</var>. The macro <code>LOG_MAKEPRI</code> generates a |
| facility/priority from a facility and a priority, as in the following |
| example: |
| |
| <pre class="smallexample"> LOG_MAKEPRI(LOG_USER, LOG_WARNING) |
| </pre> |
| <p>The possible values for the facility code are (macros): |
| |
| <!-- Internally, there is also LOG_KERN, but LOG_KERN == 0, which means --> |
| <!-- if you try to use it here, just selects default. --> |
| <dl> |
| <dt><code>LOG_USER</code><a name="index-LOG_005fUSER-2036"></a><dd>A miscellaneous user process |
| <br><dt><code>LOG_MAIL</code><a name="index-LOG_005fMAIL-2037"></a><dd>Mail |
| <br><dt><code>LOG_DAEMON</code><a name="index-LOG_005fDAEMON-2038"></a><dd>A miscellaneous system daemon |
| <br><dt><code>LOG_AUTH</code><a name="index-LOG_005fAUTH-2039"></a><dd>Security (authorization) |
| <br><dt><code>LOG_SYSLOG</code><a name="index-LOG_005fSYSLOG-2040"></a><dd>Syslog |
| <br><dt><code>LOG_LPR</code><a name="index-LOG_005fLPR-2041"></a><dd>Central printer |
| <br><dt><code>LOG_NEWS</code><a name="index-LOG_005fNEWS-2042"></a><dd>Network news (e.g. Usenet) |
| <br><dt><code>LOG_UUCP</code><a name="index-LOG_005fUUCP-2043"></a><dd>UUCP |
| <br><dt><code>LOG_CRON</code><a name="index-LOG_005fCRON-2044"></a><dd>Cron and At |
| <br><dt><code>LOG_AUTHPRIV</code><a name="index-LOG_005fAUTHPRIV-2045"></a><dd>Private security (authorization) |
| <br><dt><code>LOG_FTP</code><a name="index-LOG_005fFTP-2046"></a><dd>Ftp server |
| <br><dt><code>LOG_LOCAL0</code><a name="index-LOG_005fLOCAL0-2047"></a><dd>Locally defined |
| <br><dt><code>LOG_LOCAL1</code><a name="index-LOG_005fLOCAL1-2048"></a><dd>Locally defined |
| <br><dt><code>LOG_LOCAL2</code><a name="index-LOG_005fLOCAL2-2049"></a><dd>Locally defined |
| <br><dt><code>LOG_LOCAL3</code><a name="index-LOG_005fLOCAL3-2050"></a><dd>Locally defined |
| <br><dt><code>LOG_LOCAL4</code><a name="index-LOG_005fLOCAL4-2051"></a><dd>Locally defined |
| <br><dt><code>LOG_LOCAL5</code><a name="index-LOG_005fLOCAL5-2052"></a><dd>Locally defined |
| <br><dt><code>LOG_LOCAL6</code><a name="index-LOG_005fLOCAL6-2053"></a><dd>Locally defined |
| <br><dt><code>LOG_LOCAL7</code><a name="index-LOG_005fLOCAL7-2054"></a><dd>Locally defined |
| </dl> |
| |
| <p>Results are undefined if the facility code is anything else. |
| |
| <p><strong>NB:</strong> <code>syslog</code> recognizes one other facility code: that of |
| the kernel. But you can't specify that facility code with these |
| functions. If you try, it looks the same to <code>syslog</code> as if you are |
| requesting the default facility. But you wouldn't want to anyway, |
| because any program that uses the GNU C library is not the kernel. |
| |
| <p>You can use just a priority code as <var>facility_priority</var>. In that |
| case, <code>syslog</code> assumes the default facility established when the |
| Syslog connection was opened. See <a href="Syslog-Example.html#Syslog-Example">Syslog Example</a>. |
| |
| <p>The possible values for the priority code are (macros): |
| |
| <dl> |
| <dt><code>LOG_EMERG</code><a name="index-LOG_005fEMERG-2055"></a><dd>The message says the system is unusable. |
| <br><dt><code>LOG_ALERT</code><a name="index-LOG_005fALERT-2056"></a><dd>Action on the message must be taken immediately. |
| <br><dt><code>LOG_CRIT</code><a name="index-LOG_005fCRIT-2057"></a><dd>The message states a critical condition. |
| <br><dt><code>LOG_ERR</code><a name="index-LOG_005fERR-2058"></a><dd>The message describes an error. |
| <br><dt><code>LOG_WARNING</code><a name="index-LOG_005fWARNING-2059"></a><dd>The message is a warning. |
| <br><dt><code>LOG_NOTICE</code><a name="index-LOG_005fNOTICE-2060"></a><dd>The message describes a normal but important event. |
| <br><dt><code>LOG_INFO</code><a name="index-LOG_005fINFO-2061"></a><dd>The message is purely informational. |
| <br><dt><code>LOG_DEBUG</code><a name="index-LOG_005fDEBUG-2062"></a><dd>The message is only for debugging purposes. |
| </dl> |
| |
| <p>Results are undefined if the priority code is anything else. |
| |
| <p>If the process does not presently have a Syslog connection open (i.e., |
| it did not call <code>openlog</code>), <code>syslog</code> implicitly opens the |
| connection the same as <code>openlog</code> would, with the following defaults |
| for information that would otherwise be included in an <code>openlog</code> |
| call: The default identification string is the program name. The |
| default default facility is <code>LOG_USER</code>. The default for all the |
| connection options in <var>options</var> is as if those bits were off. |
| <code>syslog</code> leaves the Syslog connection open. |
| |
| <p>If the <samp><span class="file">dev/log</span></samp> socket is not open and connected, <code>syslog</code> |
| opens and connects it, the same as <code>openlog</code> with the |
| <code>LOG_NDELAY</code> option would. |
| |
| <p><code>syslog</code> leaves <samp><span class="file">/dev/log</span></samp> open and connected unless its attempt |
| to send the message failed, in which case <code>syslog</code> closes it (with the |
| hope that a future implicit open will restore the Syslog connection to a |
| usable state). |
| |
| <p>Example: |
| |
| <pre class="smallexample"> |
| #include <syslog.h> |
| syslog (LOG_MAKEPRI(LOG_LOCAL1, LOG_ERROR), |
| "Unable to make network connection to %s. Error=%m", host); |
| |
| </pre> |
| </blockquote></div> |
| |
| <!-- syslog.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Function: void <b>vsyslog</b> (<var>int facility_priority, char *format, va_list arglist</var>)<var><a name="index-vsyslog-2063"></a></var><br> |
| <blockquote> |
| <p>This is functionally identical to <code>syslog</code>, with the BSD style variable |
| length argument. |
| |
| </blockquote></div> |
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