X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=man%2Fsystemd-nspawn.xml;h=8adcd946b0438e6da634576eefc780a99ada068a;hb=5b7d4c1c164d91b8c28c3dcd3921ad9863953ffa;hp=2fa00e80c0c71696cdae51d87db80f132597d4a3;hpb=a7f5bb1eafadbb08c8528baae588bbe773a37e79;p=elogind.git

diff --git a/man/systemd-nspawn.xml b/man/systemd-nspawn.xml
index 2fa00e80c..8adcd946b 100644
--- a/man/systemd-nspawn.xml
+++ b/man/systemd-nspawn.xml
@@ -49,7 +49,17 @@
 
         <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"><replaceable>COMMAND</replaceable>
+                        <arg choice="opt" rep="repeat">ARGS</arg>
+                        </arg>
+                </cmdsynopsis>
+                <cmdsynopsis>
+                        <command>systemd-nspawn</command>
+                        <arg choice="plain">-b</arg>
+                        <arg choice="opt" rep="repeat">OPTIONS</arg>
+                        <arg choice="opt" rep="repeat">ARGS</arg>
                 </cmdsynopsis>
         </refsynopsisdiv>
 
@@ -114,7 +124,10 @@
                 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
@@ -125,10 +138,16 @@
         <refsect1>
                 <title>Options</title>
 
-                <para>If no arguments are passed the container is set
-                up and a shell started in it, otherwise the passed
-                command and arguments are executed in it. The
-                following options are understood:</para>
+                <para>If option <option>-b</option> is specified, the
+                arguments are used as arguments for the init
+                binary. Otherwise, <replaceable>COMMAND</replaceable>
+                specifies the program to launch in the container, and
+                the remaining arguments are used as arguments for this
+                program. If <option>-b</option> is not used and no
+                arguments are specifed, a shell is launched in the
+                container.</para>
+
+                <para>The following options are understood:</para>
 
                 <variablelist>
                         <varlistentry>
@@ -164,7 +183,10 @@
                                 <listitem><para>Automatically search
                                 for an init binary and invoke it
                                 instead of a shell or a user supplied
-                                program.</para></listitem>
+                                program. If this option is used, arguments
+                                specified on the command line are used
+                                as arguments for the init binary.
+                                </para></listitem>
                         </varlistentry>
 
                         <varlistentry>
@@ -262,13 +284,13 @@
                                 not linked. If <literal>host</literal>,
                                 the journal files are stored on the
                                 host file system (beneath
-                                <filename>/var/log/journal/&lt;machine-id&gt;</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/&lt;machine-id&gt;</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),
@@ -292,6 +314,26 @@
                                 <listitem><para>Equivalent to
                                 <option>--link-journal=guest</option>.</para></listitem>
                         </varlistentry>
+
+                        <varlistentry>
+                                <term><option>--bind=</option></term>
+                                <term><option>--bind-ro=</option></term>
+
+                                <listitem><para>Bind mount a file or
+                                directory from the host into the
+                                container. Either takes a path
+                                argument -- in which case the
+                                specified path will be mounted from
+                                the host to the same path in the
+                                container --, or a colon-separated
+                                pair of paths -- in which case the
+                                first specified path is the source in
+                                the host, and the second path is the
+                                destination in the container. The
+                                <option>--bind-ro=</option> option
+                                creates read-only bind
+                                mount.</para></listitem>
+                        </varlistentry>
                 </variablelist>
 
         </refsect1>
@@ -318,7 +360,6 @@
                 distribution into the directory
                 <filename>~/debian-tree/</filename> and then spawns a
                 shell in a namespace container in it.</para>
-
         </refsect1>
 
         <refsect1>
@@ -332,6 +373,24 @@
                 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>
                 <title>Exit status</title>
 
@@ -344,6 +403,7 @@
                 <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>pacman</refentrytitle><manvolnum>8</manvolnum></citerefentry>