<refsynopsisdiv>
<cmdsynopsis>
- <command>systemd-nspawn <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="opt">COMMAND</arg> <arg choice="opt" rep="repeat">ARGS</arg></command>
+ <command>systemd-nspawn</command>
+ <arg choice="opt" rep="repeat">OPTIONS</arg>
+ <arg choice="opt">COMMAND</arg>
+ <arg choice="opt" rep="repeat">ARGS</arg>
</cmdsynopsis>
</refsynopsisdiv>
container.</para>
<para>Use a tool like
- <citerefentry><refentrytitle>yum</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- or
+ <citerefentry><refentrytitle>yum</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ or
+ <citerefentry><refentrytitle>pacman</refentrytitle><manvolnum>8</manvolnum></citerefentry>
to set up an OS directory tree suitable as file system
hierarchy for <command>systemd-nspawn</command>
containers.</para>
see each other. The PID namespace separation of the
two containers is complete and the containers will
share very few runtime objects except for the
- underlying file system.</para>
+ underlying file system. It is however possible to
+ enter an existing container, see
+ <link linkend='example-nsenter'>Example 4</link> below.
+ </para>
<para><command>systemd-nspawn</command> implements the
<ulink
<variablelist>
<varlistentry>
- <term><option>--help</option></term>
<term><option>-h</option></term>
+ <term><option>--help</option></term>
<listitem><para>Prints a short help
text and exits.</para></listitem>
</varlistentry>
<varlistentry>
- <term><option>--directory=</option></term>
<term><option>-D</option></term>
+ <term><option>--directory=</option></term>
<listitem><para>Directory to use as
file system root for the namespace
</varlistentry>
<varlistentry>
- <term><option>--boot</option></term>
<term><option>-b</option></term>
+ <term><option>--boot</option></term>
<listitem><para>Automatically search
for an init binary and invoke it
</varlistentry>
<varlistentry>
- <term><option>--user=</option></term>
<term><option>-u</option></term>
+ <term><option>--user=</option></term>
<listitem><para>Run the command
under specified user, create home
</varlistentry>
<varlistentry>
- <term><option>--controllers=</option></term>
<term><option>-C</option></term>
+ <term><option>--controllers=</option></term>
<listitem><para>Makes the container appear in
other hierarchies than the name=systemd:/ one.
not linked. If <literal>host</literal>,
the journal files are stored on the
host file system (beneath
- <filename>/var/log/journal/<machine-id></filename>)
+ <filename>/var/log/journal/<replaceable>machine-id</replaceable></filename>)
and the subdirectory is bind-mounted
into the container at the same
location. If <literal>guest</literal>,
the journal files are stored on the
guest file system (beneath
- <filename>/var/log/journal/<machine-id></filename>)
+ <filename>/var/log/journal/<replaceable>machine-id</replaceable></filename>)
and the subdirectory is symlinked into the host
at the same location. If
<literal>auto</literal> (the default),
distribution into the directory
<filename>~/debian-tree/</filename> and then spawns a
shell in a namespace container in it.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Example 3</title>
+
+ <programlisting># pacstrap -c -d ~/arch-tree/ base
+# systemd-nspawn -bD ~/arch-tree/</programlisting>
+
+ <para>This installs a mimimal Arch Linux distribution into
+ the directory <filename>~/arch-tree/</filename> and then
+ boots an OS in a namespace container in it.</para>
+ </refsect1>
+
+ <refsect1 id='example-nsenter'>
+ <title>Example 4</title>
+
+ <para>To enter the container, PID of one of the
+ processes sharing the new namespaces must be used.
+ <command>systemd-nspawn</command> prints the PID
+ (as viewed from the outside) of the launched process,
+ and it can be used to enter the container.</para>
+
+ <programlisting># nsenter -muinpt $PID</programlisting>
+ <para><citerefentry><refentrytitle>nsenter</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ is part of
+ <ulink url="https://github.com/karelzak/util-linux">util-linux</ulink>.
+ Kernel support for entering namespaces was added in
+ Linux 3.8.</para>
</refsect1>
<refsect1>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>unshare</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>yum</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ <citerefentry><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>pacman</refentrytitle><manvolnum>8</manvolnum></citerefentry>
</para>
</refsect1>