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<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 214</span><hr><div class="refentry"><a name="sd_watchdog_enabled"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_watchdog_enabled — Check whether the service manager expects watchdog keep-alive notifications from a service</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">#include <systemd/sd-daemon.h></pre><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_watchdog_enabled</b>(</code></td><td>int <var class="pdparam">unset_environment</var>, </td></tr><tr><td> </td><td>const uint64_t *<var class="pdparam">usec</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm214188950800"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="function">sd_watchdog_enabled()</code> may
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be called by a service to detect whether the service
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manager expects regular keep-alive watchdog
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notification events from it, and the timeout after
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which the manager will act on the service if it did
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not get such a notification.</p><p>If the <em class="parameter"><code>unset_environment</code></em>
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parameter is non-zero,
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<code class="function">sd_watchdog_enabled()</code> will unset
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the <code class="varname">$WATCHDOG_USEC</code> and
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<code class="varname">$WATCHDOG_PID</code> environment variables
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before returning (regardless of whether the function call
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itself succeeded or not). Further calls to
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<code class="function">sd_watchdog_enabled()</code> will then
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return with zero, but the variable is no longer
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inherited by child processes.</p><p>If the <em class="parameter"><code>usec</code></em> parameter is
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non-NULL, <code class="function">sd_watchdog_enabled()</code>
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will return the timeout in µs for the watchdog
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logic. The service manager will usually terminate a
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service when it did not get a notification message
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within the specified time after startup and after each
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previous message. It is recommended that a daemon
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sends a keep-alive notification message to the service
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manager every half of the time returned
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here. Notification messages may be sent with
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<a href="sd_notify.html"><span class="citerefentry"><span class="refentrytitle">sd_notify</span>(3)</span></a>
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with a message string of
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"<code class="literal">WATCHDOG=1</code>".</p><p>To enable service supervision with the watchdog
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logic, use <code class="varname">WatchdogSec=</code> in service
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files. See
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<a href="systemd.service.html"><span class="citerefentry"><span class="refentrytitle">systemd.service</span>(5)</span></a>
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for details.</p></div><div class="refsect1"><a name="idm214190777808"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p>On failure, this call returns a negative
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errno-style error code. If the service manager expects
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watchdog keep-alive notification messages to be sent,
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> 0 is returned, otherwise 0 is returned. Only if
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the return value is > 0, the
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<em class="parameter"><code>usec</code></em> parameter is valid after
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the call.</p></div><div class="refsect1"><a name="idm214190410576"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p><a name="pkgconfig-text"></a>These APIs are implemented as a shared
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library, which can be compiled and linked to with the
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<code class="constant">libsystemd</code> <a href="pkg-config.html"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
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file.</p><p>Internally, this functions parses the
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<code class="varname">$WATCHDOG_PID</code> and
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<code class="varname">$WATCHDOG_USEC</code> environment
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variable. The call will ignore these variables if
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<code class="varname">$WATCHDOG_PID</code> does containe the PID
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of the current process, under the assumption that in
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that case, the variables were set for a different
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process further up the process tree.</p></div><div class="refsect1"><a name="idm214189186128"></a><h2 id="Environment">Environment<a class="headerlink" title="Permalink to this headline" href="#Environment">¶</a></h2><div class="variablelist"><dl class="variablelist"><dt id="$WATCHDOG_PID"><span class="term"><code class="varname">$WATCHDOG_PID</code></span><a class="headerlink" title="Permalink to this term" href="#%24WATCHDOG_PID">¶</a></dt><dd><p>Set by the system
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manager for supervised process for
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which watchdog support is enabled, and
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contains the PID of that process. See
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above for details.</p></dd><dt id="$WATCHDOG_USEC"><span class="term"><code class="varname">$WATCHDOG_USEC</code></span><a class="headerlink" title="Permalink to this term" href="#%24WATCHDOG_USEC">¶</a></dt><dd><p>Set by the system
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manager for supervised process for
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which watchdog support is enabled, and
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contains the watchdog timeout in µs
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See above for
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details.</p></dd></dl></div></div><div class="refsect1"><a name="idm214189804720"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
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<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
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<a href="sd-daemon.html"><span class="citerefentry"><span class="refentrytitle">sd-daemon</span>(3)</span></a>,
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<a href="daemon.html"><span class="citerefentry"><span class="refentrytitle">daemon</span>(7)</span></a>,
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<a href="systemd.service.html"><span class="citerefentry"><span class="refentrytitle">systemd.service</span>(5)</span></a>,
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<a href="sd_notify.html"><span class="citerefentry"><span class="refentrytitle">sd_notify</span>(3)</span></a>
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</p></div></div></body></html>
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