Самый быстрый способ резервного копирования одного файла?

Иногда может потребоваться установка пакета whois:

dpkg: dependency problems prevent configuration of ovtr:

ovtr depends on whois; however:  Package whois is not installed.

Тогда мы просто выполним:

sudo apt-get install whois

The following NEW packages will be installed: whois

0 upgraded, 1 newly installed, 0 to remove and 4 not upgraded.

After this operation, 164 kB of additional disk space will be used.
Get:1 http://archive.ubuntu.com/ubuntu/ trusty/main whois amd64 5.1.1 [30,2 kB]
Fetched 30,2 kB in 0s (39,8 kB/s)
Selecting previously unselected package whois.
(Reading database ... 355631 files and directories currently installed.)
Preparing to unpack .../archives/whois_5.1.1_amd64.deb ...
Unpacking whois (5.1.1) ...
Processing triggers for man-db (2.6.7.1-1ubuntu1) ...
Setting up whois (5.1.1) ...
Setting up ovtr (1.6.3-1) ...