Hi, On Mon, Jun 13, 2016 at 10:04:29PM +0200, Holger Wansing wrote: > Joost van Baal-Ilić <joostvb-debian-doc-20160530-1@mdcc.cx> wrote: > > > > Current Debian FAQ in SVN says, in customizing.sgml : > > > > <sect id="booting">Every distribution seems to have a different boot-up > > method. Tell me about Debian's. > > > > <p>Like all Unices, Debian boots up by executing the program <tt>init</tt> > > <footnote>As of this writing, the unstable release for Debian GNU/Linux is > > replacing sysvinit with <prgn/systemd/, a system and service manager for Linux. For > > more information see <url id="https://wiki.debian.org/systemd";>.</footnote>. > > The configuration file for <tt>init</tt> (which is <tt>/etc/inittab</tt>) > > specifies that > > > > This is obsolete. > > > > I guess we should update it; and I'm in favor of mentioning e.g. openrc and > > systemd-sysv as alternative ways to boot a Debian system. > > > > > > Some pointers I've found: > > > > https://www.debian.org/devel/tech-ctte#status > > > > 2014-02-11 Bug #727708: The committee decided that the default init system for > > Linux architectures in jessie should be systemd. > > [CTTE #727708] Default init system for Debian > > https://lists.debian.org/debian-devel-announce/2014/02/msg00005.html > > > > 2014-08-01 Bug #746715: The technical committee expects maintainers to continue > > to support the multiple available init systems. > > https://lists.debian.org/debian-devel-announce/2014/08/msg00001.html > > [CTTE #746715] Continuing support for multiple init systems > > > > 2014-11-15 Bug #746578:The committee decided that systemd-shim should be the > > first listed alternative dependency of libpam-systemd instead of systemd-sysv. > > https://lists.debian.org/debian-devel-announce/2014/11/msg00010.html > > [CTTE #746578] libpam-systemd to switch alternate dependency ordering > > > > https://lists.debian.org/debian-devel-announce/2014/11/msg00000.html > > [CTTE #762194] On automatic init system switching on upgrade > > > > > > Thoughts? I am willing to write a draft text. > > I think this change should be done. Thank you Holger. I've now finally comitted some text. I've also used https://bugs.debian.org/#787152 : a nice patch contributed by Alan Lee. I feel some proofreading is needed here. My commit r11725 is attached. Bye, Joost
Index: customizing.sgml
===================================================================
--- customizing.sgml (revision 11724)
+++ customizing.sgml (working copy)
@@ -13,6 +13,7 @@
environment variable. For details, see the manual page
<manref name="papersize" section="5">.
+
<sect id="hardwareaccess">How can I provide access to hardware peripherals,
without compromising security?
@@ -34,11 +35,13 @@
devices when the system starts; if this happens to the hardware peripherals you
are interested in, you will have to adjust the rules at <tt>/etc/udev</tt>.
+
<sect id="consolefont">How do I load a console font on startup the Debian way?
<p>The <package/kbd/ package supports this,
edit the <tt>/etc/kbd/config</tt> file.
+
<sect id="appdefaults">How can I configure an X11 program's application
defaults?
@@ -48,14 +51,81 @@
marked as configuration files, so their contents will be preserved during
upgrades.
-<sect id="booting">Every distribution seems to have a different boot-up
- method. Tell me about Debian's.
-<p>Like all Unices, Debian boots up by executing the program <tt>init</tt>
-<footnote>As of this writing, the unstable release for Debian GNU/Linux is
-replacing sysvinit with <prgn/systemd/, a system and service manager for Linux. For
-more information see <url id="https://wiki.debian.org/systemd";>.</footnote>.
-The configuration file for <tt>init</tt> (which is <tt>/etc/inittab</tt>)
+<sect id="booting">How does a Debian system boot?</sect>
+
+<p>Like all Unices, Debian boots up by executing the program <tt>init</tt>.
+Like most Linux distributions, a default Debian system uses <tt>systemd</tt> as
+the init implementation. BTW: traditional System-V style init, and even more,
+is supported too, see below. <footnote>In 2014, Debian changed its default
+init system from System V init to systemd. Debian 8 "jessie" in april 2015 was
+the first release to ship with systemd as default init. Four <url
+id='https://www.debian.org/devel/tech-ctte#status' name='decisions'> of the
+Debian Technical Committee were involved:
+
+<url id='https://lists.debian.org/20140211193904.GX24404@rzlab.ucr.edu'
+name='Bug #727708'> 2014-02-11: "The committee decided that the default init
+system for Linux architectures in jessie should be systemd."
+
+<url
+id='https://lists.debian.org/20140801023630.GF12356@teltox.donarmstrong.com'
+name='Bug #746715'> 2014-08-01: "The technical committee expects maintainers to
+continue to support the multiple available init systems", and merge reasonable
+contributions.
+
+<url
+id='https://lists.debian.org/20141116001628.GO32192@teltox.donarmstrong.com'
+name='Bug #746578'> 2014-11-15: "The committee decided that systemd-shim should
+be the first listed alternative dependency of libpam-systemd instead of
+systemd-sysv." This decision made it easier to keep running a non-systemd
+Debian system.
+
+<url
+id='https://lists.debian.org/21592.61064.527547.410074@chiark.greenend.org.uk'
+name='Bug #762194'>2017-11-04: "On automatic init system switching on upgrade"
+
+</footnote>
+
+<p>Instead of <i>runlevels</i>, as used on traditional
+System-V style Unix systems, systemd provides <i>targets</i>. You may check
+the default target by the command
+
+ <example>systemctl get-default</example>
+
+<p>During boot-up, systemd start the services or other targets listed in the
+default target file <tt>/lib/systemd/system/default.target</tt>. The files for
+these services and targets are installed during Debian package installation.
+If you explicitly do not wish to run a packages service during boot-up, instead
+of removing the installed package, you can run the command
+
+ <example>systemctl disable <i>package</i>.service</example>
+
+where <i>package</i>.service is the service file installed in
+<tt>/lib/systemd/system</tt>.</p>
+
+<p>Service file <tt>/lib/systemd/rc.local.service</tt> provides an easy way to
+run customized scripts in the file <tt>/etc/rc.local</tt> after boot-up,
+similar to what's offered on Debian systems running System-V style init.
+Beware: this script will fail if it has interaction to the console such as
+asking for a user password or if it tries to clear the screen.</p>
+
+<p>You can check the status of any service by the command
+
+ <example>systemctl status package.service</example>
+
+.</p>
+
+<p>For more information on systemd for Debian, see <nurl
+id="https://wiki.debian.org/systemd";>.
+
+
+<sect id="sysvinit">And how about Debian and traditional System V init</sect>
+
+ other ways of booting?</sect>
+
+Debian supports booting using traditional System V init, via the sysvinit-core package.
+
+The configuration file for System V <tt>init</tt> (which is <tt>/etc/inittab</tt>)
specifies that the first script to be executed should be
<tt>/etc/init.d/rcS</tt>. This script runs all of the scripts in
<tt>/etc/rcS.d/</tt> by forking subprocesses
@@ -106,42 +176,18 @@
<p>Note that <prgn/invoke-rc.d/ should not be used to call the
<tt>/etc/init.d/</tt> scripts, <prgn/service/ should be used instead.
-<sect id="custombootscripts">What other facilities are provided
- to customize the boot process besides
- <tt>rc.local</tt>?
-<p>The <tt>rc.local</tt> script is executed at the end of each multiuser
-runlevel. In Debian it is configured to do nothing. This provides
-customisation of the boot process, but might not be sufficient
-for all situations.
+<sect id='altboot'>And are there yet other ways of booting a Debian system?</sect>
-<p>Suppose a system needs to execute script <tt>foo</tt> on start-up,
-or on entry to a particular (System V) runlevel. Then the system
-administrator should:
-<list>
- <item>Enter the script <tt>foo</tt> into the directory <tt>/etc/init.d/</tt>.
- <item>Run the Debian command <tt>update-rc.d</tt> with appropriate
- arguments, to specify which runlevels should start the service, and which
- runlevels should stop the service.
- <item>Consider rebooting the system to check that the service starts
- correctly (assuming that you've asked for it to be started in the
- default runlevel). Otherwise, manually start it by running
- `<tt>/etc/init.d/foo start</tt>'.
-</list>
+<p>If you do like System V init, but don't like the /etc/rc?.d/* links, you
+could install the <package/file-rc/ package. That will convert the links into
+one single configuration file /etc/runlevel.conf instead.</p>
-<p>One might, for example, cause the script <tt>foo</tt> to execute at
-boot-up, by putting it in <tt>/etc/init.d/</tt> and running
-<tt>update-rc.d foo defaults 19</tt>. The argument `<tt>defaults</tt>' refers
-to the default runlevels, which means (at least in absence of any LSB comment
-block to the contrary) to start the service in runlevels 2 through 5,
-and to stop the service in runlevels 0, 1 and 6.
-(Any LSB Default-Start and Default-Stop directives in <tt>foo</tt> take
-precedence when using the sysv-rc version of update-rc.d, but are
-ignored by file-rc's variant (v0.8.10 and higher) of update-rc.d.)
-The argument `<tt>19</tt>' ensures that <tt>foo</tt> is called after all
-scripts whose number is less than 19 have completed, and before all scripts
-whose number is 20 or greater.
+<p>If you like neither System V nor systemd, you might like <package/openrc/ or
+<package/runit/ or <package/daemontools/.</p>
+
+
<sect id="interconffiles">How does the package management system deal with
packages that contain configuration files for other packages?
Index: debian/changelog
===================================================================
--- debian/changelog (revision 11724)
+++ debian/changelog (working copy)
@@ -11,6 +11,16 @@
been working on this package for 3 years. As requested by Mattia Rizzolo /
MIA team. Thanks Mattia. Simon: thanks and please do keep committing!
(Closes: #873264)
+ * 2017-11-30: customizing.sgml: Add section "booting": "How does a Debian system
+ boot?", with patch with notes on systemd contributed by Alan Lee. Thanks!
+ Add pointers to relevant 2014 CTTE decisions (The systemd debate).
+ Rename section "booting": "Every distribution seems to have a different
+ boot-up method. Tell me about Debian's." to "sysvinit": "And how about
+ Debian and traditional System V init". Drop section "custombootscripts":
+ "What other facilities are provided to customize the boot process besides
+ rc.local?": it is relevant for System V init only and therefore does not
+ belong here. Add section 'altboot': "And are there yet other ways of booting
+ a Debian system?" mentioning e.g. openrc. (Closes: #787152)
[ Javier Fernández-Sanguino ]
* 2017-06-20: ftparchives.sgml: Update releases and names. Update links in
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