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1 | <?xml version='1.0'?> <!--*-nxml-*--> |
2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
4 | ||
5 | <!-- | |
6 | This file is part of systemd. | |
7 | ||
8 | Copyright 2010 Lennart Poettering | |
9 | ||
10 | systemd is free software; you can redistribute it and/or modify it | |
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11 | under the terms of the GNU Lesser General Public License as published by |
12 | the Free Software Foundation; either version 2.1 of the License, or | |
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13 | (at your option) any later version. |
14 | ||
15 | systemd is distributed in the hope that it will be useful, but | |
16 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
5430f7f2 | 18 | Lesser General Public License for more details. |
8f7a3c14 | 19 | |
5430f7f2 | 20 | You should have received a copy of the GNU Lesser General Public License |
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21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. |
22 | --> | |
23 | ||
24 | <refentry id="systemd-nspawn"> | |
25 | ||
26 | <refentryinfo> | |
27 | <title>systemd-nspawn</title> | |
28 | <productname>systemd</productname> | |
29 | ||
30 | <authorgroup> | |
31 | <author> | |
32 | <contrib>Developer</contrib> | |
33 | <firstname>Lennart</firstname> | |
34 | <surname>Poettering</surname> | |
35 | <email>lennart@poettering.net</email> | |
36 | </author> | |
37 | </authorgroup> | |
38 | </refentryinfo> | |
39 | ||
40 | <refmeta> | |
41 | <refentrytitle>systemd-nspawn</refentrytitle> | |
42 | <manvolnum>1</manvolnum> | |
43 | </refmeta> | |
44 | ||
45 | <refnamediv> | |
46 | <refname>systemd-nspawn</refname> | |
47 | <refpurpose>Spawn a namespace container for debugging, testing and building</refpurpose> | |
48 | </refnamediv> | |
49 | ||
50 | <refsynopsisdiv> | |
51 | <cmdsynopsis> | |
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52 | <command>systemd-nspawn</command> |
53 | <arg choice="opt" rep="repeat">OPTIONS</arg> | |
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54 | <arg choice="opt"><replaceable>COMMAND</replaceable> |
55 | <arg choice="opt" rep="repeat">ARGS</arg> | |
56 | </arg> | |
57 | </cmdsynopsis> | |
58 | <cmdsynopsis> | |
59 | <command>systemd-nspawn</command> | |
60 | <arg choice="plain">-b</arg> | |
61 | <arg choice="opt" rep="repeat">OPTIONS</arg> | |
1fd96121 | 62 | <arg choice="opt" rep="repeat">ARGS</arg> |
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63 | </cmdsynopsis> |
64 | </refsynopsisdiv> | |
65 | ||
66 | <refsect1> | |
67 | <title>Description</title> | |
68 | ||
69 | <para><command>systemd-nspawn</command> may be used to | |
70 | run a command or OS in a light-weight namespace | |
71 | container. In many ways it is similar to | |
72 | <citerefentry><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
73 | but more powerful since it fully virtualizes the file | |
9f7dad77 | 74 | system hierarchy, as well as the process tree, the |
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75 | various IPC subsystems and the host and domain |
76 | name.</para> | |
77 | ||
78 | <para><command>systemd-nspawn</command> limits access | |
79 | to various kernel interfaces in the container to | |
80 | read-only, such as <filename>/sys</filename>, | |
81 | <filename>/proc/sys</filename> or | |
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82 | <filename>/sys/fs/selinux</filename>. Network |
83 | interfaces and the system clock may not be changed | |
84 | from within the container. Device nodes may not be | |
85 | created. The host system cannot be rebooted and kernel | |
86 | modules may not be loaded from within the | |
87 | container.</para> | |
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88 | |
89 | <para>Note that even though these security precautions | |
90 | are taken <command>systemd-nspawn</command> is not | |
91 | suitable for secure container setups. Many of the | |
92 | security features may be circumvented and are hence | |
93 | primarily useful to avoid accidental changes to the | |
94 | host system from the container. The intended use of | |
95 | this program is debugging and testing as well as | |
96 | building of packages, distributions and software | |
97 | involved with boot and systems management.</para> | |
98 | ||
99 | <para>In contrast to | |
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100 | <citerefentry><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry> <command>systemd-nspawn</command> |
101 | may be used to boot full Linux-based operating systems | |
102 | in a container.</para> | |
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103 | |
104 | <para>Use a tool like | |
4d62fb42 | 105 | <citerefentry><refentrytitle>yum</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
04ac7992 | 106 | <citerefentry><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
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107 | or |
108 | <citerefentry><refentrytitle>pacman</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
8f7a3c14 | 109 | to set up an OS directory tree suitable as file system |
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110 | hierarchy for <command>systemd-nspawn</command> |
111 | containers.</para> | |
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112 | |
113 | <para>Note that <command>systemd-nspawn</command> will | |
114 | mount file systems private to the container to | |
115 | <filename>/dev</filename>, | |
2b583ce6 | 116 | <filename>/run</filename> and similar. These will |
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117 | not be visible outside of the container, and their |
118 | contents will be lost when the container exits.</para> | |
119 | ||
120 | <para>Note that running two | |
121 | <command>systemd-nspawn</command> containers from the | |
122 | same directory tree will not make processes in them | |
9f7dad77 | 123 | see each other. The PID namespace separation of the |
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124 | two containers is complete and the containers will |
125 | share very few runtime objects except for the | |
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126 | underlying file system. Use |
127 | <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s | |
128 | <command>login</command> command to request an | |
129 | additional login prompt in a running container.</para> | |
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130 | |
131 | <para><command>systemd-nspawn</command> implements the | |
132 | <ulink | |
133 | url="http://www.freedesktop.org/wiki/Software/systemd/ContainerInterface">Container | |
134 | Interface</ulink> specification.</para> | |
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135 | |
136 | <para>As a safety check | |
137 | <command>systemd-nspawn</command> will verify the | |
fb69ed55 | 138 | existence of <filename>/etc/os-release</filename> in |
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139 | the container tree before starting the container (see |
140 | <citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry>). It | |
141 | might be necessary to add this file to the container | |
142 | tree manually if the OS of the container is too old to | |
143 | contain this file out-of-the-box.</para> | |
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144 | </refsect1> |
145 | ||
146 | <refsect1> | |
147 | <title>Incompatibility with Auditing</title> | |
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148 | |
149 | <para>Note that the kernel auditing subsystem is | |
150 | currently broken when used together with | |
151 | containers. We hence recommend turning it off entirely | |
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152 | by booting with <literal>audit=0</literal> on the |
153 | kernel command line, or by turning it off at kernel | |
79640424 | 154 | build time. If auditing is enabled in the kernel, |
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155 | operating systems booted in an nspawn container might |
156 | refuse log-in attempts.</para> | |
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157 | </refsect1> |
158 | ||
159 | <refsect1> | |
160 | <title>Options</title> | |
161 | ||
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162 | <para>If option <option>-b</option> is specified, the |
163 | arguments are used as arguments for the init | |
164 | binary. Otherwise, <replaceable>COMMAND</replaceable> | |
165 | specifies the program to launch in the container, and | |
166 | the remaining arguments are used as arguments for this | |
167 | program. If <option>-b</option> is not used and no | |
168 | arguments are specifed, a shell is launched in the | |
169 | container.</para> | |
170 | ||
171 | <para>The following options are understood:</para> | |
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172 | |
173 | <variablelist> | |
174 | <varlistentry> | |
a41fe3a2 | 175 | <term><option>-h</option></term> |
a7f5bb1e | 176 | <term><option>--help</option></term> |
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177 | |
178 | <listitem><para>Prints a short help | |
179 | text and exits.</para></listitem> | |
180 | </varlistentry> | |
181 | ||
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182 | <varlistentry> |
183 | <term><option>--version</option></term> | |
184 | ||
185 | <listitem><para>Prints a version string | |
186 | and exits.</para></listitem> | |
187 | </varlistentry> | |
188 | ||
8f7a3c14 | 189 | <varlistentry> |
ab1f0633 | 190 | <term><option>-D</option></term> |
a7f5bb1e | 191 | <term><option>--directory=</option></term> |
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192 | |
193 | <listitem><para>Directory to use as | |
194 | file system root for the namespace | |
79640424 | 195 | container. If omitted, the current |
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196 | directory will be |
197 | used.</para></listitem> | |
198 | </varlistentry> | |
199 | ||
0f0dbc46 | 200 | <varlistentry> |
0f0dbc46 | 201 | <term><option>-b</option></term> |
a7f5bb1e | 202 | <term><option>--boot</option></term> |
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203 | |
204 | <listitem><para>Automatically search | |
205 | for an init binary and invoke it | |
206 | instead of a shell or a user supplied | |
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207 | program. If this option is used, arguments |
208 | specified on the command line are used | |
209 | as arguments for the init binary. | |
210 | </para></listitem> | |
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211 | </varlistentry> |
212 | ||
687d0825 | 213 | <varlistentry> |
4f755fc6 | 214 | <term><option>-u</option></term> |
a7f5bb1e | 215 | <term><option>--user=</option></term> |
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216 | |
217 | <listitem><para>Run the command | |
218 | under specified user, create home | |
219 | directory and cd into it. As rest | |
220 | of systemd-nspawn, this is not | |
221 | the security feature and limits | |
222 | against accidental changes only. | |
223 | </para></listitem> | |
224 | </varlistentry> | |
225 | ||
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226 | <varlistentry> |
227 | <term><option>-M</option></term> | |
228 | <term><option>--machine=</option></term> | |
229 | ||
230 | <listitem><para>Sets the machine name | |
231 | for this container. This name may be | |
232 | used to identify this container on the | |
233 | host, and is used to initialize the | |
234 | container's hostname (which the | |
235 | container can choose to override, | |
79640424 | 236 | however). If not specified, the last |
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237 | component of the root directory of the |
238 | container is used.</para></listitem> | |
239 | </varlistentry> | |
240 | ||
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241 | <varlistentry> |
242 | <term><option>--slice=</option></term> | |
243 | ||
244 | <listitem><para>Make the container | |
245 | part of the specified slice, instead | |
246 | of the | |
247 | <filename>machine.slice</filename>.</para> | |
248 | </listitem> | |
249 | </varlistentry> | |
250 | ||
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251 | <varlistentry> |
252 | <term><option>--uuid=</option></term> | |
253 | ||
e9dd9f95 | 254 | <listitem><para>Set the specified UUID |
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255 | for the container. The init system |
256 | will initialize | |
257 | <filename>/etc/machine-id</filename> | |
258 | from this if this file is not set yet. | |
259 | </para></listitem> | |
260 | </varlistentry> | |
261 | ||
a41fe3a2 | 262 | <varlistentry> |
ff01d048 | 263 | <term><option>--private-network</option></term> |
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264 | |
265 | <listitem><para>Turn off networking in | |
266 | the container. This makes all network | |
267 | interfaces unavailable in the | |
268 | container, with the exception of the | |
269 | loopback device.</para></listitem> | |
270 | </varlistentry> | |
271 | ||
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272 | <varlistentry> |
273 | <term><option>--read-only</option></term> | |
274 | ||
275 | <listitem><para>Mount the root file | |
e9dd9f95 | 276 | system read-only for the |
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277 | container.</para></listitem> |
278 | </varlistentry> | |
279 | ||
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280 | <varlistentry> |
281 | <term><option>--capability=</option></term> | |
282 | ||
283 | <listitem><para>List one or more | |
284 | additional capabilities to grant the | |
e9dd9f95 | 285 | container. Takes a comma-separated |
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286 | list of capability names, see |
287 | <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
288 | for more information. Note that the | |
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289 | following capabilities will be granted |
290 | in any way: CAP_CHOWN, | |
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291 | CAP_DAC_OVERRIDE, CAP_DAC_READ_SEARCH, |
292 | CAP_FOWNER, CAP_FSETID, CAP_IPC_OWNER, | |
293 | CAP_KILL, CAP_LEASE, | |
294 | CAP_LINUX_IMMUTABLE, | |
295 | CAP_NET_BIND_SERVICE, | |
296 | CAP_NET_BROADCAST, CAP_NET_RAW, | |
297 | CAP_SETGID, CAP_SETFCAP, CAP_SETPCAP, | |
298 | CAP_SETUID, CAP_SYS_ADMIN, | |
299 | CAP_SYS_CHROOT, CAP_SYS_NICE, | |
300 | CAP_SYS_PTRACE, CAP_SYS_TTY_CONFIG, | |
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301 | CAP_SYS_RESOURCE, CAP_SYS_BOOT, |
302 | CAP_AUDIT_WRITE, | |
303 | CAP_AUDIT_CONTROL.</para></listitem> | |
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304 | </varlistentry> |
305 | ||
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306 | <varlistentry> |
307 | <term><option>--drop-capability=</option></term> | |
308 | ||
309 | <listitem><para>Specify one or more | |
310 | additional capabilities to drop for | |
311 | the container. This allows running the | |
312 | container with fewer capabilities than | |
313 | the default (see above).</para></listitem> | |
314 | </varlistentry> | |
315 | ||
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316 | <varlistentry> |
317 | <term><option>--link-journal=</option></term> | |
318 | ||
319 | <listitem><para>Control whether the | |
320 | container's journal shall be made | |
79640424 | 321 | visible to the host system. If enabled, |
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322 | allows viewing the container's journal |
323 | files from the host (but not vice | |
324 | versa). Takes one of | |
325 | <literal>no</literal>, | |
326 | <literal>host</literal>, | |
327 | <literal>guest</literal>, | |
328 | <literal>auto</literal>. If | |
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329 | <literal>no</literal>, the journal is |
330 | not linked. If <literal>host</literal>, | |
57fb9fb5 | 331 | the journal files are stored on the |
27407a01 | 332 | host file system (beneath |
e670b166 | 333 | <filename>/var/log/journal/<replaceable>machine-id</replaceable></filename>) |
27407a01 | 334 | and the subdirectory is bind-mounted |
57fb9fb5 | 335 | into the container at the same |
27407a01 | 336 | location. If <literal>guest</literal>, |
57fb9fb5 | 337 | the journal files are stored on the |
27407a01 | 338 | guest file system (beneath |
e670b166 | 339 | <filename>/var/log/journal/<replaceable>machine-id</replaceable></filename>) |
27407a01 | 340 | and the subdirectory is symlinked into the host |
57fb9fb5 | 341 | at the same location. If |
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342 | <literal>auto</literal> (the default), |
343 | and the right subdirectory of | |
57fb9fb5 | 344 | <filename>/var/log/journal</filename> |
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345 | exists, it will be bind mounted |
346 | into the container. If the | |
6b4991cf | 347 | subdirectory does not exist, no |
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348 | linking is performed. Effectively, |
349 | booting a container once with | |
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350 | <literal>guest</literal> or |
351 | <literal>host</literal> will link the | |
27407a01 | 352 | journal persistently if further on |
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353 | the default of <literal>auto</literal> |
354 | is used.</para></listitem> | |
355 | </varlistentry> | |
356 | ||
357 | <varlistentry> | |
358 | <term><option>-j</option></term> | |
359 | ||
360 | <listitem><para>Equivalent to | |
361 | <option>--link-journal=guest</option>.</para></listitem> | |
362 | </varlistentry> | |
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363 | |
364 | <varlistentry> | |
365 | <term><option>--bind=</option></term> | |
366 | <term><option>--bind-ro=</option></term> | |
367 | ||
368 | <listitem><para>Bind mount a file or | |
369 | directory from the host into the | |
370 | container. Either takes a path | |
371 | argument -- in which case the | |
372 | specified path will be mounted from | |
373 | the host to the same path in the | |
374 | container --, or a colon-separated | |
375 | pair of paths -- in which case the | |
376 | first specified path is the source in | |
377 | the host, and the second path is the | |
378 | destination in the container. The | |
379 | <option>--bind-ro=</option> option | |
380 | creates read-only bind | |
381 | mount.</para></listitem> | |
382 | </varlistentry> | |
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383 | </variablelist> |
384 | ||
385 | </refsect1> | |
386 | ||
387 | <refsect1> | |
388 | <title>Example 1</title> | |
389 | ||
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390 | <programlisting># yum -y --releasever=19 --nogpg --installroot=/srv/mycontainer --disablerepo='*' --enablerepo=fedora install systemd passwd yum fedora-release vim-minimal |
391 | # systemd-nspawn -bD /srv/mycontainer</programlisting> | |
8f7a3c14 | 392 | |
25f5971b | 393 | <para>This installs a minimal Fedora distribution into |
845c5324 | 394 | the directory <filename noindex='true'>/srv/mycontainer/</filename> and |
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395 | then boots an OS in a namespace container in |
396 | it.</para> | |
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397 | </refsect1> |
398 | ||
399 | <refsect1> | |
400 | <title>Example 2</title> | |
401 | ||
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402 | <programlisting># debootstrap --arch=amd64 unstable ~/debian-tree/ |
403 | # systemd-nspawn -D ~/debian-tree/</programlisting> | |
8f7a3c14 | 404 | |
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405 | <para>This installs a minimal Debian unstable |
406 | distribution into the directory | |
407 | <filename>~/debian-tree/</filename> and then spawns a | |
408 | shell in a namespace container in it.</para> | |
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409 | </refsect1> |
410 | ||
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411 | <refsect1> |
412 | <title>Example 3</title> | |
413 | ||
414 | <programlisting># pacstrap -c -d ~/arch-tree/ base | |
415 | # systemd-nspawn -bD ~/arch-tree/</programlisting> | |
416 | ||
417 | <para>This installs a mimimal Arch Linux distribution into | |
418 | the directory <filename>~/arch-tree/</filename> and then | |
419 | boots an OS in a namespace container in it.</para> | |
420 | </refsect1> | |
421 | ||
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422 | <refsect1> |
423 | <title>Example 4</title> | |
424 | ||
425 | <programlisting># mv ~/arch-tree /var/lib/container/arch | |
426 | # systemctl enable systemd-nspawn@arch.service | |
427 | # systemctl start systemd-nspawn@arch.service</programlisting> | |
428 | ||
429 | <para>This makes the Arch Linux container part of the | |
430 | <filename>multi-user.target</filename> on the host. | |
431 | </para> | |
432 | </refsect1> | |
433 | ||
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434 | <refsect1> |
435 | <title>Exit status</title> | |
436 | ||
437 | <para>The exit code of the program executed in the | |
438 | container is returned.</para> | |
439 | </refsect1> | |
440 | ||
441 | <refsect1> | |
442 | <title>See Also</title> | |
443 | <para> | |
444 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
445 | <citerefentry><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
25f5971b | 446 | <citerefentry><refentrytitle>yum</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
4d62fb42 | 447 | <citerefentry><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
431c72dc | 448 | <citerefentry><refentrytitle>pacman</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
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449 | <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>, |
450 | <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
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451 | </para> |
452 | </refsect1> | |
453 | ||
454 | </refentry> |