All you need to do to run top is command:
top
Top is an interactive tool. This means that you can continue to issue commands or options for top while it is running. Run top, then try:
- u
- d
- m
Top is useful for finding resource-hogging processes so you can kill them, among other things.
There’s an exhaustive listing of command and display options at About.com: http://linux.about.com/od/commands/l/blcmdl1_top.htm.
The top command leads the list of “20 Linux System Monitoring Tools Every SysAdmin Should Know” by Vivek Gite, at http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html