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22 | <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 219</span><hr><div class="refentry"><a name="systemd-halt.service"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>systemd-halt.service, systemd-poweroff.service, systemd-reboot.service, systemd-kexec.service, systemd-shutdown — System shutdown logic</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><p><code class="filename">systemd-halt.service</code></p><p><code class="filename">systemd-poweroff.service</code></p><p><code class="filename">systemd-reboot.service</code></p><p><code class="filename">systemd-kexec.service</code></p><p><code class="filename">/usr/lib/systemd/systemd-shutdown</code></p></div><div class="refsect1"><a name="idm140022452053280"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="filename">systemd-halt.service</code> is a system |
| 23 | service that is pulled in by <code class="filename">halt.target</code> and | |
| 24 | is responsible for the actual system halt. Similarly, | |
| 25 | <code class="filename">systemd-poweroff.service</code> is pulled in by | |
| 26 | <code class="filename">poweroff.target</code>, | |
| 27 | <code class="filename">systemd-reboot.service</code> by | |
| 28 | <code class="filename">reboot.target</code> and | |
| 29 | <code class="filename">systemd-kexec.service</code> by | |
| 30 | <code class="filename">kexec.target</code> to execute the respective | |
| 31 | actions.</p><p>When these services are run, they ensure that PID 1 is | |
| 32 | replaced by the | |
| 33 | <code class="filename">/usr/lib/systemd/systemd-shutdown</code> tool which | |
| 34 | is then responsible for the actual shutdown. Before shutting down, | |
| 35 | this binary will try to unmount all remaining file systems, | |
| 36 | disable all remaining swap devices, detach all remaining storage | |
| 37 | devices and kill all remaining processes.</p><p>It is necessary to have this code in a separate binary | |
| 38 | because otherwise rebooting after an upgrade might be broken — the | |
| 39 | running PID 1 could still depend on libraries which are not | |
| 40 | available any more, thus keeping the file system busy, which then | |
| 41 | cannot be re-mounted read-only.</p><p>Immediately before executing the actual system | |
| 42 | halt/poweroff/reboot/kexec <code class="filename">systemd-shutdown</code> | |
| 43 | will run all executables in | |
| 44 | <code class="filename">/usr/lib/systemd/system-shutdown/</code> and pass | |
| 45 | one arguments to them: either "<code class="literal">halt</code>", | |
| 46 | "<code class="literal">poweroff</code>", "<code class="literal">reboot</code>" or | |
| 47 | "<code class="literal">kexec</code>", depending on the chosen action. All | |
| 48 | executables in this directory are executed in parallel, and | |
| 49 | execution of the action is not continued before all executables | |
| 50 | finished.</p><p>Note that <code class="filename">systemd-halt.service</code> (and the | |
| 51 | related units) should never be executed directly. Instead, trigger | |
| 52 | system shutdown with a command such as "<code class="literal">systemctl | |
| 53 | halt</code>" or suchlike.</p></div><div class="refsect1"><a name="idm140022455939872"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p> | |
| 54 | <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>, | |
| 55 | <a href="systemctl.html"><span class="citerefentry"><span class="refentrytitle">systemctl</span>(1)</span></a>, | |
| 56 | <a href="systemd.special.html"><span class="citerefentry"><span class="refentrytitle">systemd.special</span>(7)</span></a>, | |
| 57 | <a href="http://man7.org/linux/man-pages/man2/reboot.2.html"><span class="citerefentry"><span class="refentrytitle">reboot</span>(2)</span></a>, | |
| 58 | <a href="systemd-suspend.service.html"><span class="citerefentry"><span class="refentrytitle">systemd-suspend.service</span>(8)</span></a> | |
| 59 | </p></div></div></body></html> |