Retrieve CPU usage and memory usage of a single process on Linux?

Question

I want to get the CPU and memory usage of a single process on Linux - I know the PID. Hopefully, I can get it every second and write it to a CSV using the \'watch\' command

Answer 1

ps -p  -o %cpu,%mem,cmd

(You can leave off "cmd" but that might be helpful in debugging).

Note that this gives average CPU usage of the process over the time it has been running.