1 | <?xml version="1.0" encoding="ISO-8859-1"?> |
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2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
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3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [ |
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4 | <!ENTITY % general-entities SYSTEM "../../general.ent"> |
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5 | %general-entities; |
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6 | ]> |
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7 | |
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8 | <sect1 id="ch-scripts-clock"> |
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9 | <?dbhtml filename="clock.html"?> |
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10 | |
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11 | <title>Configuring the system clock</title> |
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12 | |
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13 | <indexterm zone="ch-scripts-clock"> |
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14 | <primary sortas="d-clock">clock</primary> |
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15 | <secondary>configuring</secondary></indexterm> |
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16 | |
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17 | <para>This section discusses how to configure the |
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18 | <command>systemd-timedated</command> system service, which configures |
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19 | system clock and timezone.</para> |
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20 | |
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21 | <para>Systemd provides a <command>timedatectl</command> utility which is |
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22 | used to communicate with <command>systemd-timedated</command>. It can be used |
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23 | to set the system clock in local time or UTC time, depending on the hardware |
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24 | clock setting. By default, <command>systemd-timedated</command> will assume |
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25 | that clock is set to UTC time.</para> |
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26 | |
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27 | <para>If you cannot remember whether or not the hardware clock is set to UTC, |
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28 | find out by running the <userinput>hwclock --localtime --show</userinput> |
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29 | command. This will display what the current time is according to the hardware |
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30 | clock. If this time matches whatever your watch says, then the hardware clock is |
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31 | set to local time. If the output from <command>hwclock</command> is not local |
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32 | time, chances are it is set to UTC time. Verify this by adding or subtracting |
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33 | the proper amount of hours for the timezone to the time shown by |
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34 | <command>hwclock</command>. For example, if you are currently in the MST |
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35 | timezone, which is also known as GMT -0700, add seven hours to the local |
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36 | time.</para> |
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37 | |
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38 | <para><command>systemd-timedated</command> reads |
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39 | <filename>/etc/adjtime</filename>, and depending on the contents of the file, |
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40 | it sets the clock to either UTC or local time.</para> |
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41 | |
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42 | <para>Create the <filename>/etc/adjtime</filename> file with the following |
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43 | contents if your hardware clock is set to local time:</para> |
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44 | |
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45 | <screen role="nodump"><userinput>cat > /etc/adjtime << "EOF" |
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46 | <literal>0.0 0 0.0 |
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47 | 0 |
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48 | LOCAL</literal> |
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49 | EOF</userinput></screen> |
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50 | |
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51 | <para>If <filename>/etc/adjtime</filename> isn't present at first boot, |
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52 | <command>systemd-timedated</command> will assume that hardware clock is |
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53 | set to UTC and adjust the file according to that.</para> |
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54 | |
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55 | <para>If your clock is set to local time, tell |
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56 | <command>systemd-timedated</command> about it by running the following |
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57 | command:</para> |
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58 | |
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59 | <screen role="nodump"><userinput>timedatectl set-local-rtc 1</userinput></screen> |
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60 | |
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61 | <para><command>timedatectl</command> can also be used to change system time and |
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62 | time zone.</para> |
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63 | |
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64 | <para>To change your current system time, issue:</para> |
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65 | |
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66 | <screen role="nodump"><userinput>timedatectl set-time YYYY:MM:DD HH:MM:SS</userinput></screen> |
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67 | |
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68 | <para>Hardware clock will also be updated accordingly.</para> |
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69 | |
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70 | <para>To change your current time zone, issue:</para> |
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71 | |
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72 | <screen role="nodump"><userinput>timedatectl set-timezone TIMEZONE</userinput></screen> |
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73 | |
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74 | <para>You can get list of available time zones by running:</para> |
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75 | |
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76 | <screen role="nodump"><userinput>timedatectl list-timezones</userinput></screen> |
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77 | |
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78 | <note><para>Please note that <command>timedatectl</command> command can |
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79 | be used only on a system booted with systemd.</para></note> |
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80 | |
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81 | </sect1> |
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