如果再次运行该命令，只有更改后的文件被复制，为您节省了稍后的同步时间。

If you run it again, only the changed files are copied over, saving you time later on synchronizations.

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更改时间戳的一种方式是在文本编辑器中打开文件，然后保存它。

One way to change the time stamp is to open the file in a text editor and save it.

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这个文件还可以记录其他事件，如启动的日期和时间，以及最近的运行级别更改。

The same file also records other events, such as the date and time of the boot and the last run level change.

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