The apt commands have been introduced to solve this problem. apt consists some of the most widely used features from apt-get, apt-cache and apt-config leaving aside obscure and seldom used features.
The apt-cache command line tool is used for searching apt 's software package cache. In simple words, this tool is used to search software packages, collect information about packages and also search for what packages are available and ready for installation on Debian- or Ubuntu-based systems.
apt - How do I search for available packages from the command-line ...
Use this: sudo apt update # Fetches the list of available updates sudo apt upgrade # Installs some updates; does not remove packages sudo apt full-upgrade # Installs updates; may also remove some packages, if needed sudo apt autoremove # Removes any old packages that are no longer needed Documentation about each apt option can be found in the the manpages for apt. These are also available by ...
apt - How to install updates via command line? - Ask Ubuntu
The reason for this change is that when adding an OpenPGP key that's used to sign an APT repository to /etc/apt/trusted.gpg or /etc/apt/trusted.gpg.d, the key is unconditionally trusted by APT on all other repositories configured on the system that don't have a signed-by (see below) option, even the official Debian / Ubuntu repositories.
apt - How do I fix the GPG error "NO_PUBKEY"? - Ask Ubuntu
The apt command provides a convenient subset of the functionality of various other apt- commands (e.g., apt-get, apt-cache), with colorized display and progress bars.