To list all installed package on a Linux system depends on which distribution you are running and the package management mode used.
In this tutorial, we are going to look at commands on some of the notable and popularly used distros.
NOTE: You can pipe the less command OR redirected to a text file using the redirection operator (>). Below are examples
example | less
example > installed_packages.txt
Red Hat/Fedora Core/CentOS Linux:
FreeBSD / OpenBSD:
Ubuntu / Debian / Linux Mint: