12.1 Repositories

Linux is essentially comprised of a set of base packages that provide the core functionality of the operating system together with a range of other packages and modules that add functionality and features on top of the base operating system.

When Ubuntu is first installed, a number of different packages will be installed depending on the software options selected during the installation phase. Once the system is up and running, however, additional software can be installed as needed. Typically, all software that is part of Ubuntu (in other words software that is not provided by a third party vendor) is downloaded and installed on the system using the Advanced Package Tool (apt) command. As we have seen in earlier chapters, this typically consists of a command similar to the following being issued at the command prompt:

# apt install apache2

When such a command is issued, the requested software is downloaded from a remote repository and installed on the local...