Handling applications and packages

Kali Linux packages are stored in repositories and downloaded to the system to ensure the integrity of the package. Make sure to always update the system, as mentioned in the previous chapter. The repository configuration file is located at/etc/apt/sources.list. Make sure that this file is not empty (it will be if you didn't choose the network mirror option during the installation process); if it is, your Kali will not update. 

The Advanced Packaging Tool

The Advanced Packaging Tool (APT) is used for installing or upgrading packages, along with all of the required dependencies. The APT can also be used to upgrade a complete distribution of Kali:

• apt-get update or apt update: This command is used to synchronize the local package index files with their sources, as defined in /etc/apt/sources.list. The update command should always be used first, before performing an upgrade or dist-upgrade.
• apt-get upgrade or apt upgrade: This command is used to install the newest...