Discussion on: A small byte of bash aliases and functions.

For your process finding one, you might want to exclude the grep command itself, depending on what system you're on. On a Mac, for example, you'll get the process used to grep listed, which is generally not what you want. Also on a Mac, ps -aux will fail if there isn't a user called "x" because ps interprets commands differently depending whether you use a dash or not (I know!).

alias pid='ps aux | grep -v grep | grep'

Or if you're only interested in the PID (as implied by the alias name, you can use pgrep which fits nicely with pkill because without any other options it just returns the PID.

I know you tagged this with #linux but I think it's good to make things as general as possible so if you have to work on a BSD system or a Mac you can re-use the same commands.