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authorLennart Poettering <lennart@poettering.net>2016-02-10 21:29:45 +0100
committerLennart Poettering <lennart@poettering.net>2016-02-10 23:48:29 +0100
commit6e004630fea24f1d4d76f8b062f9f862ba237140 (patch)
treebcbc4e0b13fd15036c2b47afec406c8e4b24b777
parent926db6521b16f5fbf9c532142fd243ee6cea4ca8 (diff)
man: document rescue.target and emergency.target in more detail
Fixes: #2523
-rw-r--r--man/systemd.special.xml37
1 files changed, 27 insertions, 10 deletions
diff --git a/man/systemd.special.xml b/man/systemd.special.xml
index 0a37f65956..055d854555 100644
--- a/man/systemd.special.xml
+++ b/man/systemd.special.xml
@@ -204,12 +204,22 @@
<varlistentry>
<term><filename>emergency.target</filename></term>
<listitem>
- <para>A special target unit that starts an emergency shell
- on the main console. This unit is supposed to be used with
- the kernel command line option
- <varname>systemd.unit=</varname> and has otherwise little
- use.
- </para>
+ <para>A special target unit that starts an emergency shell on the main console. This target does not pull in
+ any serices or mounts. It is the most minimal version of starting the system in order to acquire an
+ interactive shell; the only processes running are usually just the system manager (PID 1) and the shell
+ process. This unit is supposed to be used with the kernel command line option
+ <varname>systemd.unit=</varname>; it is also used when a file system check on a required file system fails,
+ and boot-up cannot continue. Compare with <filename>rescue.target</filename>, which serves a similar purpose,
+ but also starts the most basic services and mounts all file systems.</para>
+
+ <para>Use the <literal>systemd.unit=emergency.target</literal> kernel command line option to boot into this
+ mode. A short alias for this kernel command line option is <literal>emergency</literal>, for compatibility
+ with SysV.</para>
+
+ <para>In many ways booting into <filename>emergency.target</filename> is similar to the effect of booting
+ with <literal>init=/bin/sh</literal> on the kernel command line, except that emergency mode provides you with
+ the full system and service manager, and allows starting individual units in order to continue the boot
+ process in steps.</para>
</listitem>
</varlistentry>
<varlistentry>
@@ -440,11 +450,18 @@
<varlistentry>
<term><filename>rescue.target</filename></term>
<listitem>
- <para>A special target unit for setting up the base system
- and a rescue shell.</para>
+ <para>A special target unit that pulls in the base system (including system mounts) and spawns a rescue
+ shell. Isolate to this target in order to administer the system in single-user mode with all file systems
+ mounted but with no services running, except for the most basic. Compare with
+ <filename>emergency.target</filename>, which is much more reduced and does not provide the file systems or
+ most basic services.</para>
- <para><filename>runlevel1.target</filename> is an alias for
- this target unit, for compatibility with SysV.</para>
+ <para><filename>runlevel1.target</filename> is an alias for this target unit, for compatibility with
+ SysV.</para>
+
+ <para>Use the <literal>systemd.unit=rescue.target</literal> kernel command line option to boot into this
+ mode. A short alias for this kernel command line option is <literal>1</literal>, for compatibility with
+ SysV.</para>
</listitem>
</varlistentry>
<varlistentry>