diff options
Diffstat (limited to 'man/systemd-nspawn.xml')
| -rw-r--r-- | man/systemd-nspawn.xml | 65 |
1 files changed, 59 insertions, 6 deletions
diff --git a/man/systemd-nspawn.xml b/man/systemd-nspawn.xml index 1cfef93df1..86cdb4e124 100644 --- a/man/systemd-nspawn.xml +++ b/man/systemd-nspawn.xml @@ -249,15 +249,68 @@ </varlistentry> <varlistentry> + <term><option>-a</option></term> + <term><option>--as-pid2</option></term> + + <listitem><para>Invoke the shell or specified program as process ID (PID) 2 instead of PID 1 (init). By + default, if neither this option nor <option>--boot</option> is used, the selected binary is run as process with + PID 1, a mode only suitable for programs that are aware of the special semantics that the process with PID 1 + has on UNIX. For example, it needs to reap all processes reparented to it, and should implement + <command>sysvinit</command> compatible signal handling (specifically: it needs to reboot on SIGINT, reexecute + on SIGTERM, reload configuration on SIGHUP, and so on). With <option>--as-pid2</option> a minimal stub init + process is run as PID 1 and the selected binary is executed as PID 2 (and hence does not need to implement any + special semantics). The stub init process will reap processes as necessary and react appropriately to + signals. It is recommended to use this mode to invoke arbitrary commands in containers, unless they have been + modified to run correctly as PID 1. Or in other words: this switch should be used for pretty much all commands, + except when the command refers to an init or shell implementation, as these are generally capable of running + correctly as PID 1). This option may not be combined with <option>--boot</option> or + <option>--share-system</option>.</para> + </listitem> + </varlistentry> + + <varlistentry> <term><option>-b</option></term> <term><option>--boot</option></term> - <listitem><para>Automatically search for an init binary and - invoke it instead of a shell or a user supplied program. If - this option is used, arguments specified on the command line - are used as arguments for the init binary. This option may not - be combined with <option>--share-system</option>. - </para></listitem> + <listitem><para>Automatically search for an init binary and invoke it as PID 1, instead of a shell or a user + supplied program. If this option is used, arguments specified on the command line are used as arguments for the + init binary. This option may not be combined with <option>--as-pid2</option> or + <option>--share-system</option>.</para> + + <para>The following table explains the different modes of invocation and relationship to + <option>--as-pid2</option> (see above):</para> + + <table> + <title>Invocation Mode</title> + <tgroup cols='2' align='left' colsep='1' rowsep='1'> + <colspec colname="switch" /> + <colspec colname="explanation" /> + <thead> + <row> + <entry>Switch</entry> + <entry>Explanation</entry> + </row> + </thead> + <tbody> + <row> + <entry>Neither <option>--as-pid2</option> nor <option>--boot</option> specified</entry> + <entry>The passed parameters are interpreted as command line, which is executed as PID 1 in the container.</entry> + </row> + + <row> + <entry><option>--as-pid2</option> specified</entry> + <entry>The passed parameters are interpreted as command line, which are executed as PID 2 in the container. A stub init process is run as PID 1.</entry> + </row> + + <row> + <entry><option>--boot</option> specified</entry> + <entry>An init binary as automatically searched and run as PID 1 in the container. The passed parameters are used as invocation parameters for this process.</entry> + </row> + + </tbody> + </tgroup> + </table> + </listitem> </varlistentry> <varlistentry> |