How to list all the commands on Ubuntu?

https://askubuntu.com/questions/403435/how-to-get-a-list-of-all-the-commands-available-for-ubuntu

Open terminal Ctrl + Alt + t and run this command:

whatis `compgen -c` | more 

This will list all commands and a simple description of each command.

If you want to save the list you can redirect the result into an output file

whatis `compgen -c` > listOfCommands.txt

So why I used whatis command. The command man whatis gives:

Each manual page has a short description available within it.
whatis searches the manual page names and displays the manual page descrip‐ tions of any name matched.

so in easy words whatis give a general. description of each command