| 1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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| 2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN" "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
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| 3 | <!ENTITY % general-entities SYSTEM "../general.ent">
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| 4 | %general-entities;
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| 5 | ]>
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| 6 | <sect1 id="ch-scripts-setclock">
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| 7 | <title>Configuring the setclock Script</title>
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| 8 | <?dbhtml filename="setclock.html"?>
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| 9 |
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| 10 | <indexterm zone="ch-scripts-setclock">
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| 11 | <primary sortas="d-setclock">setclock</primary>
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| 12 | <secondary>configuring</secondary></indexterm>
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| 13 |
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| 14 | <para>The <command>setclock</command> script reads the time from the hardware clock,
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| 15 | also known as the BIOS or the Complementary Metal Oxide Semiconductor
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| 16 | (CMOS) clock. If the hardware clock is set to UTC, this script will convert the hardware clock's time to
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| 17 | the local time using the <filename>/etc/localtime</filename> file
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| 18 | (which tells the <command>hwclock</command> program which timezone the
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| 19 | user is in). There is no way to
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| 20 | detect whether or not the hardware clock is set to UTC time, so this
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| 21 | needs to be manually configured.</para>
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| 22 |
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| 23 | <para>If you cannot remember whether or not the hardware
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| 24 | clock is set to UTC time, find out by running
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| 25 | the <userinput>hwclock --localtime --show</userinput> command. This will tell
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| 26 | what the current time is according to the hardware clock. If this time
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| 27 | matches whatever your watch says, then the hardware clock is set to
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| 28 | local time. If the output from <command>hwclock</command> is not local
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| 29 | time, chances are it is set to UTC time. Verify this by adding or
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| 30 | subtracting the proper amount of hours for the timezone to this
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| 31 | <command>hwclock</command> time. For example, if you live in the MST
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| 32 | timezone, which is also known as GMT -0700, add seven hours to the local
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| 33 | time. Then, account for Daylight Savings Time, which requires
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| 34 | subtracting an hour (or only add six in the first place) during the summer
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| 35 | months.</para>
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| 36 |
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| 37 | <para>Change the value of the <envar>UTC</envar> variable below
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| 38 | to a value of <parameter>0</parameter> (zero) if the hardware clock
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| 39 | is <emphasis>not</emphasis> set to UTC time.</para>
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| 40 |
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| 41 | <para>Create a new file <filename>/etc/sysconfig/clock</filename> by running
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| 42 | the following:</para>
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| 43 |
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| 44 | <screen><userinput>cat > /etc/sysconfig/clock << "EOF"
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| 45 | <literal># Begin /etc/sysconfig/clock
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| 46 |
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| 47 | UTC=1
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| 48 |
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| 49 | # End /etc/sysconfig/clock</literal>
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| 50 | EOF</userinput></screen>
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| 51 |
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| 52 | <para>A good hint explaining how to deal with time on LFS is available
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| 53 | at <ulink url="&hints-root;time.txt"><phrase
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| 54 | condition="pdf">http://www.linuxfromscratch.org/
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| 55 | hints/downloads/files/time.txt</phrase></ulink>. It explains issues such as
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| 56 | time zones, UTC, and the <envar>TZ</envar> environment variable.</para>
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| 57 |
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| 58 | </sect1>
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| 59 |
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