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chapter09/usage.xml
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@ -19,25 +19,29 @@
<sect2>
<title>How Do the System V Bootscripts Work?</title>
<para>Linux uses a special booting facility named SysVinit that is based on a
concept of <emphasis>run-levels</emphasis>. It can be quite different from one
system to another, so it cannot be assumed that because things worked in one
particular Linux distribution, they should work the same in LFS too. LFS has its
own way of doing things, but it respects generally accepted standards.</para>
<para>This version of LFS uses a special booting facility named SysVinit, based on a
series of <emphasis>run levels</emphasis>. The boot procedure can be quite different from one
system to another; the fact that things worked one way in a particular Linux
distribution does not guarantee they will work the same way in LFS. LFS has its
own way of doing things, but it does respect generally accepted standards.</para>
<para>There is an alternative boot procedure called <command>systemd</command>. We will
not discuss that boot process any further here. For a detailed description visit
<ulink url="https://www.linux.com/training-tutorials/understanding-and-using-systemd/"/>.</para>
<para>SysVinit (which will be referred to as <quote>init</quote> from now on)
works using a run-levels scheme. There are seven (numbered 0 to 6) run-levels
(actually, there are more run-levels, but they are for special cases and are
generally not used. See <filename>init(8)</filename> for more details), and
each one of those corresponds to the actions the computer is supposed to
perform when it starts up. The default run-level is 3. Here are the
descriptions of the different run-levels as they are implemented in LFS:</para>
uses a run levels scheme. There are seven run levels, numbered 0 to 6.
(Actually, there are more run levels, but the others are for special cases and are
generally not used. See <filename>init(8)</filename> for more details.)
Each one of the seven corresponds to actions the computer is supposed to
perform when it starts up or shuts down. The default run level is 3. Here are the
descriptions of the different run levels as they are implemented in LFS:</para>
<literallayout>0: halt the computer
1: single-user mode
2: reserved for customization, otherwise does the same as 3
2: reserved for customization, otherwise the same as 3
3: multi-user mode with networking
4: reserved for customization, otherwise does the same as 3
4: reserved for customization, otherwise the same as 3
5: same as 4, it is usually used for GUI login (like GNOME's <command>gdm</command> or LXDE's <command>lxdm</command>)
6: reboot the computer</literallayout>
@ -45,9 +49,9 @@
<para>
Classically, run level 2 above was defined as
"multi-user mode without networking", but this was only the case
many years ago when multiple users could log into a system connected via
serial ports. In today's environment it makes no sense and
we designate it now as "reserved".
many years ago when multiple users could connect to a system via
serial ports. In today's environment it makes no sense, and
we now say it is "reserved".
</para>
</note>
@ -65,8 +69,8 @@
<primary sortas="e-/etc/inittab">/etc/inittab</primary>
</indexterm>
<para>During the kernel initialization, the first program that is run
is either specified on the command line or, by default
<para>During kernel initialization, the first program that is run
(if not overridden on the command line) is
<command>init</command>. This program reads the initialization file
<filename>/etc/inittab</filename>. Create this file with:</para>
@ -101,8 +105,8 @@ s1:1:respawn:/sbin/sulogin
EOF</userinput></screen>
<para>An explanation of this initialization file is in the man page for
<emphasis>inittab</emphasis>. For LFS, the key command that is run is
<command>rc</command>. The initialization file above will instruct
<emphasis>inittab</emphasis>. In LFS, the key command is
<command>rc</command>. The initialization file above instructs
<command>rc</command> to run all the scripts starting with an S in the
<filename class="directory">/etc/rc.d/rcS.d</filename> directory
followed by all the scripts starting with an S in the <filename
@ -113,22 +117,22 @@ EOF</userinput></screen>
functions in <filename class="directory">/lib/lsb/init-functions</filename>.
This library also reads an optional configuration file,
<filename>/etc/sysconfig/rc.site</filename>. Any of the system
configuration file parameters described in subsequent sections can be
alternatively placed in this file allowing consolidation of all system
configuration parameters described in subsequent sections can be
placed in this file, allowing consolidation of all system
parameters in this one file.</para>
<para>As a debugging convenience, the functions script also logs all output
to <filename>/run/var/bootlog</filename>. Since the <filename
class="directory">/run</filename> directory is a tmpfs, this file is not
persistent across boots, however it is appended to the more permanent file
persistent across boots; however, it is appended to the more permanent file
<filename>/var/log/boot.log</filename> at the end of the boot process.</para>
<sect3 id="init-levels" >
<title>Changing Run Levels</title>
<para>Changing run-levels is done with <command>init
<para>Changing run levels is done with <command>init
<replaceable>&lt;runlevel&gt;</replaceable></command>, where
<replaceable>&lt;runlevel&gt;</replaceable> is the target run-level. For example, to
<replaceable>&lt;runlevel&gt;</replaceable> is the target run level. For example, to
reboot the computer, a user could issue the <command>init 6</command> command,
which is an alias for the <command>reboot</command> command. Likewise,
<command>init 0</command> is an alias for the <command>halt</command>
@ -136,15 +140,15 @@ EOF</userinput></screen>
<para>There are a number of directories under <filename
class="directory">/etc/rc.d</filename> that look like <filename
class="directory">rc?.d</filename> (where ? is the number of the run-level) and
class="directory">rc?.d</filename> (where ? is the number of the run level) and
<filename class="directory">rcS.d</filename>, all containing a number of
symbolic links. Some begin with a <emphasis>K</emphasis>, the others begin with
symbolic links. Some links begin with a <emphasis>K</emphasis>; the others begin with
an <emphasis>S</emphasis>, and all of them have two numbers following the
initial letter. The K means to stop (kill) a service and the S means to start a
service. The numbers determine the order in which the scripts are run, from 00
to 99&mdash;the lower the number the earlier it gets executed. When
<command>init</command> switches to another run-level, the appropriate services
are either started or stopped, depending on the runlevel chosen.</para>
to 99&mdash;the smaller the number, the sooner tht script runs. When
<command>init</command> switches to another run level, the appropriate services
are either started or stopped, depending on the run level chosen.</para>
<para>The real scripts are in <filename
class="directory">/etc/rc.d/init.d</filename>. They do the actual work, and
@ -227,21 +231,21 @@ EOF</userinput></screen>
<para>The <filename>/etc/rc.d/init.d/udev</filename> initscript starts
<command>udevd</command>, triggers any "coldplug" devices that have
already been created by the kernel and waits for any rules to complete.
already been created by the kernel, and waits for any rules to complete.
The script also unsets the uevent handler from the default of
<filename>/sbin/hotplug </filename>. This is done because the kernel no
longer needs to call out to an external binary. Instead
longer needs to call an external binary. Instead,
<command>udevd</command> will listen on a netlink socket for uevents that
the kernel raises.</para>
<para>The <command>/etc/rc.d/init.d/udev_retry</command> initscript takes
<para>The <command>/etc/rc.d/init.d/udev_retry</command> script takes
care of re-triggering events for subsystems whose rules may rely on
filesystems that are not mounted until the <command>mountfs</command>
file systems that are not mounted until the <command>mountfs</command>
script is run (in particular, <filename class="directory">/usr</filename>
and <filename class="directory">/var</filename> may cause this). This
script runs after the <command>mountfs</command> script, so those rules
(if re-triggered) should succeed the second time around. It is
configured from the <filename>/etc/sysconfig/udev_retry</filename> file;
configured by the <filename>/etc/sysconfig/udev_retry</filename> file;
any words in this file other than comments are considered subsystem names
to trigger at retry time. To find the subsystem of a device, use
<command>udevadm info --attribute-walk &lt;device&gt;</command> where
@ -260,13 +264,13 @@ EOF</userinput></screen>
<secondary>configuring</secondary></indexterm>
<para>The <command>setclock</command> script reads the time from the hardware
clock, also known as the BIOS or the Complementary Metal Oxide Semiconductor
clock, also known as the BIOS or Complementary Metal Oxide Semiconductor
(CMOS) clock. If the hardware clock is set to UTC, this script will convert the
hardware clock's time to the local time using the
<filename>/etc/localtime</filename> file (which tells the
<command>hwclock</command> program which timezone to use). There is no
<command>hwclock</command> program which time zone to use). There is no
way to detect whether or not the hardware clock is set to UTC, so this
needs to be configured manually.</para>
must be configured manually.</para>
<para>The <command>setclock</command> program is run via
<application>udev</application> when the kernel detects the hardware
@ -279,9 +283,9 @@ EOF</userinput></screen>
clock. If this time matches whatever your watch says, then the hardware clock is
set to local time. If the output from <command>hwclock</command> is not local
time, chances are it is set to UTC time. Verify this by adding or subtracting
the proper amount of hours for the timezone to the time shown by
the proper number of hours for the time zone to the time shown by
<command>hwclock</command>. For example, if you are currently in the MST
timezone, which is also known as GMT -0700, add seven hours to the local
time zone, which is also known as GMT -0700, add seven hours to the local
time.</para>
<para>Change the value of the <envar>UTC</envar> variable below
@ -325,7 +329,7 @@ EOF</userinput></screen>
<para>This section discusses how to configure the <command>console</command>
bootscript that sets up the keyboard map, console font, and console kernel log
level. If non-ASCII characters (e.g., the copyright sign, the British pound
sign and Euro symbol) will not be used and the keyboard is a U.S. one, much
sign, and the Euro symbol) will not be used and the keyboard is a U.S. one, much
of this section can be skipped. Without the configuration file, (or
equivalent settings in <filename>rc.site</filename>), the
<command>console</command> bootscript will do nothing.</para>
@ -333,11 +337,11 @@ EOF</userinput></screen>
<para>The <command>console</command> script reads the
<filename>/etc/sysconfig/console</filename> file for configuration
information. Decide which keymap and screen font will be used. Various
language-specific HOWTOs can also help with this, see <ulink
language-specific HOWTOs can also help with this; see <ulink
url="https://tldp.org/HOWTO/HOWTO-INDEX/other-lang.html"/>. If still in
doubt, look in the <filename class="directory">/usr/share/keymaps</filename>
and <filename class="directory">/usr/share/consolefonts</filename> directories
for valid keymaps and screen fonts. Read <filename>loadkeys(1)</filename> and
for valid keymaps and screen fonts. Read the <filename>loadkeys(1)</filename> and
<filename>setfont(8)</filename> manual pages to determine the correct
arguments for these programs.</para>
@ -358,7 +362,7 @@ EOF</userinput></screen>
<term>KEYMAP</term>
<listitem>
<para>This variable specifies the arguments for the
<command>loadkeys</command> program, typically, the name of keymap
<command>loadkeys</command> program, typically, the name of the keymap
to load, e.g., <quote>it</quote>. If this variable is not set, the
bootscript will not run the <command>loadkeys</command> program,
and the default kernel keymap will be used. Note that a few keymaps
@ -390,11 +394,11 @@ EOF</userinput></screen>
name, <quote>-m</quote>, and the name of the application character
map to load. E.g., in order to load the <quote>lat1-16</quote> font
together with the <quote>8859-1</quote> application character map
(as it is appropriate in the USA),
(appropriate in the USA),
<!-- because of the copyright sign -->
set this variable to <quote>lat1-16 -m 8859-1</quote>.
In UTF-8 mode, the kernel uses the application character map for
conversion of composed 8-bit key codes in the keymap to UTF-8, and thus
In UTF-8 mode, the kernel uses the application character map to
convert 8-bit key codes to UTF-8. Therefore
the argument of the "-m" parameter should be set to the encoding of the
composed key codes in the keymap.</para>
@ -404,7 +408,7 @@ EOF</userinput></screen>
<varlistentry>
<term>UNICODE</term>
<listitem>
<para>Set this variable to <quote>1</quote>, <quote>yes</quote> or
<para>Set this variable to <quote>1</quote>, <quote>yes</quote>, or
<quote>true</quote> in order to put the
console into UTF-8 mode. This is useful in UTF-8 based locales and
harmful otherwise.</para>
@ -522,7 +526,7 @@ EOF</userinput></screen>
UTF-8 mode it is a problem; e.g., for the Greek language, where one
sometimes needs to put an accent on the letter <quote>alpha</quote>.
The solution is either to avoid the use of UTF-8, or to install the
X window system that doesn't have this limitation in its input
X window system, which doesn't have this limitation, in its input
handling.</para>
</listitem>
@ -531,7 +535,7 @@ EOF</userinput></screen>
console cannot be configured to display the needed characters. Users
who need such languages should install the X Window System, fonts that
cover the necessary character ranges, and the proper input method (e.g.,
SCIM, supports a wide variety of languages).</para>
SCIM supports a wide variety of languages).</para>
</listitem>
</itemizedlist>
@ -565,7 +569,7 @@ EOF</userinput></screen>
</sect2>
<sect2 id="ch-config-sysklogd">
<title>Configuring the sysklogd Script</title>
<title>Configuring the Sysklogd Script</title>
<indexterm zone="ch-config-sysklogd">
<primary sortas="d-sysklogd">sysklogd</primary>
@ -600,8 +604,8 @@ EOF</userinput></screen>
<filename>console</filename>, and <filename>clock</filename> files in the
<filename class='directory'>/etc/sysconfig/</filename> directory. If the
associated variables are present in both these separate files and
<filename>rc.site</filename>, the values in the script specific files have
precedence. </para>
<filename>rc.site</filename>, the values in the script-specific files take
effect. </para>
<para><filename>rc.site</filename> also contains parameters that can
customize other aspects of the boot process. Setting the IPROMPT variable
@ -615,8 +619,8 @@ EOF</userinput></screen>
<title>Customizing the Boot and Shutdown Scripts</title>
<para>The LFS boot scripts boot and shut down a system in a fairly
efficient manner, but there are a few tweaks that you can make in the
rc.site file to improve speed even more and to adjust messages according
efficient manner, but there are a few tweaks you can make in the
rc.site file to improve speed even more, and to adjust messages according
to your preferences. To do this, adjust the settings in
the <filename>/etc/sysconfig/rc.site</filename> file above.</para>
@ -624,18 +628,18 @@ EOF</userinput></screen>
<listitem><para>During the boot script <filename>udev</filename>, there is
a call to <command>udev settle</command> that requires some time to
complete. This time may or may not be required depending on devices present
complete. This time may or may not be required depending on the devices
in the system. If you only have simple partitions and a single ethernet
card, the boot process will probably not need to wait for this command. To
skip it, set the variable OMIT_UDEV_SETTLE=y.</para></listitem>
<listitem><para>The boot script <filename>udev_retry</filename> also runs
<command>udev settle</command> by default. This command is only needed by
default if the <filename class='directory'>/var</filename> directory is
separately mounted. This is because the clock needs the file
<filename>/var/lib/hwclock/adjtime</filename>. Other customizations may
<command>udev settle</command> by default. This command is only needed
if the <filename class='directory'>/var</filename> directory is
separately mounted, because the clock needs the
<filename>/var/lib/hwclock/adjtime</filename> file. Other customizations may
also need to wait for udev to complete, but in many installations it is not
needed. Skip the command by setting the variable OMIT_UDEV_RETRY_SETTLE=y.
necessary. Skip the command by setting the variable OMIT_UDEV_RETRY_SETTLE=y.
</para></listitem>
<listitem><para>By default, the file system checks are silent. This can
@ -664,7 +668,7 @@ EOF</userinput></screen>
<listitem><para>During shutdown, the <command>init</command> program sends
a TERM signal to each program it has started (e.g. agetty), waits for a set
time (default 3 seconds), and sends each process a KILL signal and waits
time (default 3 seconds), then sends each process a KILL signal and waits
again. This process is repeated in the <command>sendsignals</command>
script for any processes that are not shut down by their own scripts. The
delay for <command>init</command> can be set by passing a parameter. For