Is there any command or app to monitor my system activity?

I'm looking for a command to use in the terminal or an application that allows me to see everything what is going on on my pc on real time like $ xev but not just for gui facts but for application status, or background processes.

Solution 1:

You should check out gnome-system-monitor it has all the running processes in real time as well as cpu, memory and network usage graphs(also in real time).

Solution 2:

top or htop will list the running processes.. I'm not sure if it displays all of them, maybe, if you had a big enough screen. [lol]

But, if you want all the processes running, type:

ps -ef