Sometimes you are unsure of a package name. Then, in this case, you can’t install it until you look it up. You can search for a package by using the command apt-cache search followed by your search term or keyword:
apt-cache search keyword
For example, let’s say that you want to install the wireshark package, but you can only remember that the package name has the word shark in it. In this case, you can run the command:
root@ubuntu-linux:/tmp# apt-cache search shark
dopewars - drug-dealing game set in streets of New York City
dopewars-data - drug-dealing game set in streets of New York City - data files forensics-extra - Forensics Environment - extra console components (metapackage) kernelshark - Utilities for graphically analyzing function tracing in the kernel libcrypto++-dev - General purpose cryptographic library - C++ development libshark-dev - development files for Shark
libshark0 - Shark machine learning library
libwireshark-data - network packet...