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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>sd_watchdog_enabled</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><style>
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</style><a href="index.html">Index </a>·
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<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 215</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>uint64_t *<var class="pdparam">usec</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm214185911456"></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
be called by a service to detect whether the service
manager expects regular keep-alive watchdog
notification events from it, and the timeout after
which the manager will act on the service if it did
not get such a notification.</p><p>If the <em class="parameter"><code>unset_environment</code></em>
parameter is non-zero,
<code class="function">sd_watchdog_enabled()</code> will unset
the <code class="varname">$WATCHDOG_USEC</code> and
<code class="varname">$WATCHDOG_PID</code> environment variables
before returning (regardless of whether the function call
itself succeeded or not). Further calls to
<code class="function">sd_watchdog_enabled()</code> will then
return with zero, but the variable is no longer
inherited by child processes.</p><p>If the <em class="parameter"><code>usec</code></em> parameter is
non-NULL, <code class="function">sd_watchdog_enabled()</code>
will return the timeout in µs for the watchdog
logic. The service manager will usually terminate a
service when it did not get a notification message
within the specified time after startup and after each
previous message. It is recommended that a daemon
sends a keep-alive notification message to the service
manager every half of the time returned
here. Notification messages may be sent with
<a href="sd_notify.html"><span class="citerefentry"><span class="refentrytitle">sd_notify</span>(3)</span></a>
with a message string of
"<code class="literal">WATCHDOG=1</code>".</p><p>To enable service supervision with the watchdog
logic, use <code class="varname">WatchdogSec=</code> in service
files. See
<a href="systemd.service.html"><span class="citerefentry"><span class="refentrytitle">systemd.service</span>(5)</span></a>
for details.</p></div><div class="refsect1"><a name="idm214185975520"></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
errno-style error code. If the service manager expects
watchdog keep-alive notification messages to be sent,
> 0 is returned, otherwise 0 is returned. Only if
the return value is > 0, the
<em class="parameter"><code>usec</code></em> parameter is valid after
the call.</p></div><div class="refsect1"><a name="idm214185902512"></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
library, which can be compiled and linked to with the
<code class="constant">libsystemd</code> <a href="pkg-config.html"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
file.</p><p>Internally, this functions parses the
<code class="varname">$WATCHDOG_PID</code> and
<code class="varname">$WATCHDOG_USEC</code> environment
variable. The call will ignore these variables if
<code class="varname">$WATCHDOG_PID</code> does containe the PID
of the current process, under the assumption that in
that case, the variables were set for a different
process further up the process tree.</p></div><div class="refsect1"><a name="idm214185898800"></a><h2 id="Environment">Environment<a class="headerlink" title="Permalink to this headline" href="#Environment">¶</a></h2><div class="variablelist"><dl class="variablelist"><dt id="$WATCHDOG_PID"><span class="term"><code class="varname">$WATCHDOG_PID</code></span><a class="headerlink" title="Permalink to this term" href="#%24WATCHDOG_PID">¶</a></dt><dd><p>Set by the system
manager for supervised process for
which watchdog support is enabled, and
contains the PID of that process. See
above for details.</p></dd><dt id="$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
manager for supervised process for
which watchdog support is enabled, and
contains the watchdog timeout in µs
See above for
details.</p></dd></dl></div></div><div class="refsect1"><a name="idm214186040224"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
<a href="sd-daemon.html"><span class="citerefentry"><span class="refentrytitle">sd-daemon</span>(3)</span></a>,
<a href="daemon.html"><span class="citerefentry"><span class="refentrytitle">daemon</span>(7)</span></a>,
<a href="systemd.service.html"><span class="citerefentry"><span class="refentrytitle">systemd.service</span>(5)</span></a>,
<a href="sd_notify.html"><span class="citerefentry"><span class="refentrytitle">sd_notify</span>(3)</span></a>
</p></div></div></body></html>
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