top provides an ongoing look at processor activity in real time. It displays a listing of the most CPU-intensive tasks on the system, and can provide an interactive interface for manipulating processes.

# Update every <interval> samples:
top -i <interval>

# Set the delay between updates to <delay> seconds:
top -s <delay>

# Set event counting to accumulative mode:
top -a

# Set event counting to delta mode:
top -d

# Set event counting to absolute mode:
top -e

# Do not calculate statistics on shared libraries, also known as frameworks:
top -F

# Calculate statistics on shared libraries, also known as frameworks (default):
top -f

# Print command line usage information and exit:
top -h

# Order the display by sorting on <key> in descending order
top -o <key>