如何在Ubuntu上设置时间同步

你可能设置过 cron 任务 来在特定时间备份重要文件或执行系统相关任务。也许你配置了一个日志服务器在特定时间间隔轮转日志。但如果你的时钟不同步，这些任务将无法按时执行。这就是要在 Linux 系统上设置正确的时区并保持时钟与互联网同步的原因。本指南介绍如何在 Ubuntu Linux 上设置时间同步。下面的步骤已经在 Ubuntu 18.04 上进行了测试，但是对于使用 systemd 的 timesyncd 服务的其他基于 Ubuntu 的系统它们是相同的。

在 Ubuntu 上设置时间同步

通常，我们在安装时设置时区。但是，你可以根据需要更改或设置不同的时区。

首先，让我们使用 date 命令查看 Ubuntu 系统中的当前时区：

1. <span class="pln">$ </span><span class="kwd">date</span>

示例输出：

1. <span class="typ">Tue</span><span class="pln"> </span><span class="typ">Jul</span><span class="pln"> </span><span class="lit">30</span><span class="pln"> </span><span class="lit">11</span><span class="pun">:</span><span class="lit">47</span><span class="pun">:</span><span class="lit">39</span><span class="pln"> UTC </span><span class="lit">2019</span>

如上所见，date 命令显示实际日期和当前时间。这里，我当前的时区是 UTC，代表协调世界时。

或者，你可以在 /etc/timezone 文件中查找当前时区。

1. <span class="pln">$ </span><span class="kwd">cat</span><span class="pln"> </span><span class="pun">/</span><span class="pln">etc</span><span class="pun">/</span><span class="pln">timezone</span>
2. <span class="pln">UTC</span>

现在，让我们看看时钟是否与互联网同步。只需运行：

1. <span class="pln">$ </span><span class="kwd">timedatectl</span>

示例输出：

1. <span class="typ">Local</span><span class="pln"> </span><span class="kwd">time</span><span class="pun">:</span><span class="pln"> </span><span class="typ">Tue</span><span class="pln"> </span><span class="lit">2019</span><span class="pun">-</span><span class="lit">07</span><span class="pun">-</span><span class="lit">30</span><span class="pln"> </span><span class="lit">11</span><span class="pun">:</span><span class="lit">53</span><span class="pun">:</span><span class="lit">58</span><span class="pln"> UTC</span>
2. <span class="typ">Universal</span><span class="pln"> </span><span class="kwd">time</span><span class="pun">:</span><span class="pln"> </span><span class="typ">Tue</span><span class="pln"> </span><span class="lit">2019</span><span class="pun">-</span><span class="lit">07</span><span class="pun">-</span><span class="lit">30</span><span class="pln"> </span><span class="lit">11</span><span class="pun">:</span><span class="lit">53</span><span class="pun">:</span><span class="lit">58</span><span class="pln"> UTC</span>
3. <span class="pln">RTC </span><span class="kwd">time</span><span class="pun">:</span><span class="pln"> </span><span class="typ">Tue</span><span class="pln"> </span><span class="lit">2019</span><span class="pun">-</span><span class="lit">07</span><span class="pun">-</span><span class="lit">30</span><span class="pln"> </span><span class="lit">11</span><span class="pun">:</span><span class="lit">53</span><span class="pun">:</span><span class="lit">59</span>
4. <span class="typ">Time</span><span class="pln"> zone</span><span class="pun">:</span><span class="pln"> </span><span class="typ">Etc</span><span class="pun">/</span><span class="pln">UTC </span><span class="pun">(</span><span class="pln">UTC</span><span class="pun">,</span><span class="pln"> </span><span class="pun">+</span><span class="lit">0000</span><span class="pun">)</span>
5. <span class="typ">System</span><span class="pln"> clock synchronized</span><span class="pun">:</span><span class="pln"> </span><span class="kwd">yes</span>
6. <span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span><span class="pun">.</span><span class="pln">service active</span><span class="pun">:</span><span class="pln"> </span><span class="kwd">yes</span>
7. <span class="pln">RTC </span><span class="kwd">in</span><span class="pln"> </span><span class="kwd">local</span><span class="pln"> TZ</span><span class="pun">:</span><span class="pln"> </span><span class="kwd">no</span>

如你所见，timedatectl 命令显示本地时间、世界时、时区以及系统时钟是否与互联网服务器同步，以及 systemd-timesyncd.service 是处于活动状态还是非活动状态。就我而言，系统时钟已与互联网时间服务器同步。

如果时钟不同步，你会看到下面截图中显示的 System clock synchronized: no。

时间同步已禁用。

注意：上面的截图是旧截图。这就是你看到不同日期的原因。

如果你看到 System clock synchronized: 值设置为 no，那么 timesyncd 服务可能处于非活动状态。因此，只需重启服务并看下是否正常。

1. <span class="pln">$ </span><span class="kwd">sudo</span><span class="pln"> </span><span class="kwd">systemctl</span><span class="pln"> restart </span><span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span><span class="pun">.</span><span class="pln">service</span>

现在检查 timesyncd 服务状态：

1. <span class="pln">$ </span><span class="kwd">sudo</span><span class="pln"> </span><span class="kwd">systemctl</span><span class="pln"> status </span><span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span><span class="pun">.</span><span class="pln">service</span>
2. <span class="pun">●</span><span class="pln"> </span><span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span><span class="pun">.</span><span class="pln">service </span><span class="pun">-</span><span class="pln"> </span><span class="typ">Network</span><span class="pln"> </span><span class="typ">Time</span><span class="pln"> </span><span class="typ">Synchronization</span>
3. <span class="typ">Loaded</span><span class="pun">:</span><span class="pln"> loaded </span><span class="pun">(</span><span class="str">/lib/</span><span class="kwd">systemd</span><span class="pun">/</span><span class="pln">system</span><span class="pun">/</span><span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span><span class="pun">.</span><span class="pln">service</span><span class="pun">;</span><span class="pln"> enabled</span><span class="pun">;</span><span class="pln"> vendor preset</span><span class="pun">:</span><span class="pln"> enabled</span><span class="pun">)</span>
4. <span class="typ">Active</span><span class="pun">:</span><span class="pln"> active </span><span class="pun">(</span><span class="pln">running</span><span class="pun">)</span><span class="pln"> since </span><span class="typ">Tue</span><span class="pln"> </span><span class="lit">2019</span><span class="pun">-</span><span class="lit">07</span><span class="pun">-</span><span class="lit">30</span><span class="pln"> </span><span class="lit">10</span><span class="pun">:</span><span class="lit">50</span><span class="pun">:</span><span class="lit">18</span><span class="pln"> UTC</span><span class="pun">;</span><span class="pln"> </span><span class="lit">1h</span><span class="pln"> </span><span class="lit">11min</span><span class="pln"> ago</span>
5. <span class="typ">Docs</span><span class="pun">:</span><span class="pln"> </span><span class="kwd">man</span><span class="pun">:</span><span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span><span class="pun">.</span><span class="pln">service</span><span class="pun">(</span><span class="lit">8</span><span class="pun">)</span>
6. <span class="typ">Main</span><span class="pln"> PID</span><span class="pun">:</span><span class="pln"> </span><span class="lit">498</span><span class="pln"> </span><span class="pun">(</span><span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyn</span><span class="pun">)</span>
7. <span class="typ">Status</span><span class="pun">:</span><span class="pln"> </span><span class="str">"Synchronized to time server [2001:67c:1560:8003::c7]:123 (ntp.ubuntu.com)."</span>
8. <span class="typ">Tasks</span><span class="pun">:</span><span class="pln"> </span><span class="lit">2</span><span class="pln"> </span><span class="pun">(</span><span class="pln">limit</span><span class="pun">:</span><span class="pln"> </span><span class="lit">2319</span><span class="pun">)</span>
9. <span class="typ">CGroup</span><span class="pun">:</span><span class="pln"> </span><span class="str">/system.slice/</span><span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span><span class="pun">.</span><span class="pln">service</span>
10. <span class="pun">└─</span><span class="lit">498</span><span class="pln"> </span><span class="pun">/</span><span class="pln">lib</span><span class="pun">/</span><span class="kwd">systemd</span><span class="pun">/</span><span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span>
11.  
12. <span class="typ">Jul</span><span class="pln"> </span><span class="lit">30</span><span class="pln"> </span><span class="lit">10</span><span class="pun">:</span><span class="lit">50</span><span class="pun">:</span><span class="lit">30</span><span class="pln"> ubuntuserver </span><span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span><span class="pun">[</span><span class="lit">498</span><span class="pun">]:</span><span class="pln"> </span><span class="typ">Network</span><span class="pln"> configuration changed</span><span class="pun">,</span><span class="pln"> trying to estab</span>
13. <span class="typ">Jul</span><span class="pln"> </span><span class="lit">30</span><span class="pln"> </span><span class="lit">10</span><span class="pun">:</span><span class="lit">50</span><span class="pun">:</span><span class="lit">31</span><span class="pln"> ubuntuserver </span><span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span><span class="pun">[</span><span class="lit">498</span><span class="pun">]:</span><span class="pln"> </span><span class="typ">Network</span><span class="pln"> configuration changed</span><span class="pun">,</span><span class="pln"> trying to estab</span>
14. <span class="typ">Jul</span><span class="pln"> </span><span class="lit">30</span><span class="pln"> </span><span class="lit">10</span><span class="pun">:</span><span class="lit">50</span><span class="pun">:</span><span class="lit">31</span><span class="pln"> ubuntuserver </span><span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span><span class="pun">[</span><span class="lit">498</span><span class="pun">]:</span><span class="pln"> </span><span class="typ">Network</span><span class="pln"> configuration changed</span><span class="pun">,</span><span class="pln"> trying to estab</span>
15. <span class="typ">Jul</span><span class="pln"> </span><span class="lit">30</span><span class="pln"> </span><span class="lit">10</span><span class="pun">:</span><span class="lit">50</span><span class="pun">:</span><span class="lit">32</span><span class="pln"> ubuntuserver </span><span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span><span class="pun">[</span><span class="lit">498</span><span class="pun">]:</span><span class="pln"> </span><span class="typ">Network</span><span class="pln"> configuration changed</span><span class="pun">,</span><span class="pln"> trying to estab</span>
16. <span class="typ">Jul</span><span class="pln"> </span><span class="lit">30</span><span class="pln"> </span><span class="lit">10</span><span class="pun">:</span><span class="lit">50</span><span class="pun">:</span><span class="lit">32</span><span class="pln"> ubuntuserver </span><span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span><span class="pun">[</span><span class="lit">498</span><span class="pun">]:</span><span class="pln"> </span><span class="typ">Network</span><span class="pln"> configuration changed</span><span class="pun">,</span><span class="pln"> trying to estab</span>
17. <span class="typ">Jul</span><span class="pln"> </span><span class="lit">30</span><span class="pln"> </span><span class="lit">10</span><span class="pun">:</span><span class="lit">50</span><span class="pun">:</span><span class="lit">35</span><span class="pln"> ubuntuserver </span><span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span><span class="pun">[</span><span class="lit">498</span><span class="pun">]:</span><span class="pln"> </span><span class="typ">Network</span><span class="pln"> configuration changed</span><span class="pun">,</span><span class="pln"> trying to estab</span>
18. <span class="typ">Jul</span><span class="pln"> </span><span class="lit">30</span><span class="pln"> </span><span class="lit">10</span><span class="pun">:</span><span class="lit">50</span><span class="pun">:</span><span class="lit">35</span><span class="pln"> ubuntuserver </span><span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span><span class="pun">[</span><span class="lit">498</span><span class="pun">]:</span><span class="pln"> </span><span class="typ">Network</span><span class="pln"> configuration changed</span><span class="pun">,</span><span class="pln"> trying to estab</span>
19. <span class="typ">Jul</span><span class="pln"> </span><span class="lit">30</span><span class="pln"> </span><span class="lit">10</span><span class="pun">:</span><span class="lit">50</span><span class="pun">:</span><span class="lit">35</span><span class="pln"> ubuntuserver </span><span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span><span class="pun">[</span><span class="lit">498</span><span class="pun">]:</span><span class="pln"> </span><span class="typ">Network</span><span class="pln"> configuration changed</span><span class="pun">,</span><span class="pln"> trying to estab</span>
20. <span class="typ">Jul</span><span class="pln"> </span><span class="lit">30</span><span class="pln"> </span><span class="lit">10</span><span class="pun">:</span><span class="lit">50</span><span class="pun">:</span><span class="lit">35</span><span class="pln"> ubuntuserver </span><span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span><span class="pun">[</span><span class="lit">498</span><span class="pun">]:</span><span class="pln"> </span><span class="typ">Network</span><span class="pln"> configuration changed</span><span class="pun">,</span><span class="pln"> trying to estab</span>
21. <span class="typ">Jul</span><span class="pln"> </span><span class="lit">30</span><span class="pln"> </span><span class="lit">10</span><span class="pun">:</span><span class="lit">51</span><span class="pun">:</span><span class="lit">06</span><span class="pln"> ubuntuserver </span><span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span><span class="pun">[</span><span class="lit">498</span><span class="pun">]:</span><span class="pln"> </span><span class="typ">Synchronized</span><span class="pln"> to </span><span class="kwd">time</span><span class="pln"> server </span><span class="pun">[</span><span class="lit">2001</span><span class="pun">:</span><span class="lit">67c</span><span class="pun">:</span><span class="lit">1560</span><span class="pun">:</span><span class="lit">800</span>

如果此服务已启用并处于活动状态，那么系统时钟应与互联网时间服务器同步。

你可以使用命令验证是否启用了时间同步：

1. <span class="pln">$ </span><span class="kwd">timedatectl</span>

如果仍然不起作用，请运行以下命令以启用时间同步：

1. <span class="pln">$ </span><span class="kwd">sudo</span><span class="pln"> </span><span class="kwd">timedatectl</span><span class="pln"> </span><span class="kwd">set</span><span class="pun">-</span><span class="pln">ntp </span><span class="kwd">true</span>

现在，你的系统时钟将与互联网时间服务器同步。

使用 timedatectl 命令更改时区

如果我想使用 UTC 以外的其他时区怎么办？这很容易！

首先，使用命令列出可用时区：

1. <span class="pln">$ </span><span class="kwd">timedatectl</span><span class="pln"> </span><span class="kwd">list</span><span class="pun">-</span><span class="pln">timezones</span>

你将看到类似于下图的输出。

使用 timedatectl 命令列出时区

你可以使用以下命令设置所需的时区（例如，Asia/Shanghai）：

（LCTT 译注：本文原文使用印度时区作为示例，这里为了便于使用，换为中国标准时区 CST。另外，在时区设置中，要注意 CST 这个缩写会代表四个不同的时区，因此建议使用城市和 UTC+8 来说设置。）

1. <span class="pln">$ </span><span class="kwd">sudo</span><span class="pln"> </span><span class="kwd">timedatectl</span><span class="pln"> </span><span class="kwd">set</span><span class="pun">-</span><span class="pln">timezone </span><span class="typ">Asia</span><span class="pun">/</span><span class="typ">Shanghai</span>

使用 date 命令再次检查时区是否已真正更改：

1. <span class="pln">$ </span><span class="kwd">date</span>
2. <span class="typ">Tue</span><span class="pln"> </span><span class="typ">Jul</span><span class="pln"> </span><span class="lit">30</span><span class="pln"> </span><span class="lit">20</span><span class="pun">:</span><span class="lit">22</span><span class="pun">:</span><span class="lit">33</span><span class="pln"> CST </span><span class="lit">2019</span>

或者，如果需要详细输出，请使用 timedatectl 命令：

1. <span class="pln">$ </span><span class="kwd">timedatectl</span>
2. <span class="typ">Local</span><span class="pln"> </span><span class="kwd">time</span><span class="pun">:</span><span class="pln"> </span><span class="typ">Tue</span><span class="pln"> </span><span class="lit">2019</span><span class="pun">-</span><span class="lit">07</span><span class="pun">-</span><span class="lit">30</span><span class="pln"> </span><span class="lit">20</span><span class="pun">:</span><span class="lit">22</span><span class="pun">:</span><span class="lit">35</span><span class="pln"> CST</span>
3. <span class="typ">Universal</span><span class="pln"> </span><span class="kwd">time</span><span class="pun">:</span><span class="pln"> </span><span class="typ">Tue</span><span class="pln"> </span><span class="lit">2019</span><span class="pun">-</span><span class="lit">07</span><span class="pun">-</span><span class="lit">30</span><span class="pln"> </span><span class="lit">12</span><span class="pun">:</span><span class="lit">22</span><span class="pun">:</span><span class="lit">35</span><span class="pln"> UTC</span>
4. <span class="pln">RTC </span><span class="kwd">time</span><span class="pun">:</span><span class="pln"> </span><span class="typ">Tue</span><span class="pln"> </span><span class="lit">2019</span><span class="pun">-</span><span class="lit">07</span><span class="pun">-</span><span class="lit">30</span><span class="pln"> </span><span class="lit">12</span><span class="pun">:</span><span class="lit">22</span><span class="pun">:</span><span class="lit">36</span>
5. <span class="typ">Time</span><span class="pln"> zone</span><span class="pun">:</span><span class="pln"> </span><span class="typ">Asia</span><span class="pun">/</span><span class="typ">Shanghai</span><span class="pln"> </span><span class="pun">(</span><span class="pln">CST</span><span class="pun">,</span><span class="pln"> </span><span class="pun">+</span><span class="lit">0800</span><span class="pun">)</span>
6. <span class="typ">System</span><span class="pln"> clock synchronized</span><span class="pun">:</span><span class="pln"> </span><span class="kwd">yes</span>
7. <span class="kwd">systemd</span><span class="pun">-</span><span class="pln">timesyncd</span><span class="pun">.</span><span class="pln">service active</span><span class="pun">:</span><span class="pln"> </span><span class="kwd">yes</span>
8. <span class="pln">RTC </span><span class="kwd">in</span><span class="pln"> </span><span class="kwd">local</span><span class="pln"> TZ</span><span class="pun">:</span><span class="pln"> </span><span class="kwd">no</span>

如你所见，我已将时区从 UTC 更改为 CST（中国标准时间）。（）

要切换回 UTC 时区，只需运行：

1. <span class="pln">$ </span><span class="kwd">sudo</span><span class="pln"> </span><span class="kwd">timedatectl</span><span class="pln"> </span><span class="kwd">set</span><span class="pun">-</span><span class="pln">timezone UTC</span>

使用 tzdata 更改时区

在较旧的 Ubuntu 版本中，没有 timedatectl 命令。这种情况下，你可以使用 tzdata（Time zone data）来设置时间同步。

1. <span class="pln">$ </span><span class="kwd">sudo</span><span class="pln"> dpkg</span><span class="pun">-</span><span class="pln">reconfigure tzdata</span>

选择你居住的地理区域。对我而言，我选择 Asia。选择 OK，然后按回车键。

接下来，选择与你的时区对应的城市或地区。这里，我选择了 Kolkata（LCTT 译注：中国用户请相应使用 Shanghai 等城市）。

最后，你将在终端中看到类似下面的输出。

1. <span class="typ">Current</span><span class="pln"> </span><span class="kwd">default</span><span class="pln"> </span><span class="kwd">time</span><span class="pln"> zone</span><span class="pun">:</span><span class="pln"> </span><span class="str">'Asia/Shanghai'</span>
2. <span class="typ">Local</span><span class="pln"> </span><span class="kwd">time</span><span class="pln"> </span><span class="kwd">is</span><span class="pln"> now</span><span class="pun">:</span><span class="pln"> </span><span class="typ">Tue</span><span class="pln"> </span><span class="typ">Jul</span><span class="pln"> </span><span class="lit">30</span><span class="pln"> </span><span class="lit">21</span><span class="pun">:</span><span class="lit">59</span><span class="pun">:</span><span class="lit">25</span><span class="pln"> CST </span><span class="lit">2019.</span>
3. <span class="typ">Universal</span><span class="pln"> </span><span class="typ">Time</span><span class="pln"> </span><span class="kwd">is</span><span class="pln"> now</span><span class="pun">:</span><span class="pln"> </span><span class="typ">Tue</span><span class="pln"> </span><span class="typ">Jul</span><span class="pln"> </span><span class="lit">30</span><span class="pln"> </span><span class="lit">13</span><span class="pun">:</span><span class="lit">59</span><span class="pun">:</span><span class="lit">25</span><span class="pln"> UTC </span><span class="lit">2019.</span>

在图形模式下配置时区

有些用户可能对命令行方式不太满意。如果你是其中之一，那么你可以轻松地在图形模式的系统设置面板中进行设置。

点击 Super 键（Windows 键），在 Ubuntu dash 中输入 settings，然后点击设置图标。

从 Ubuntu dash 启动系统的设置

或者，单击位于 Ubuntu 桌面右上角的向下箭头，然后单击左上角的“设置”图标。

从顶部面板启动系统的设置

在下一个窗口中，选择“细节”，然后单击“日期与时间”选项。打开“自动的日期与时间”和“自动的时区”。