Helpful Linux Commands

Consider this my Linux workbench. I plan on using this post to record useful Linux commands as I have a tendency to forget things.

lsof -I will show all in use ports.
lsof will show was files are loaded in memory.
netstat -nap will also show all in use ports, and some additional information.
cat /etc/services will show you all the allocated ports. When picking ports, make sure they are not allocated already.
ps -eo size,cmd Prints out the processes and their memory sizes.