# The linux fuser command has a special option for port conflicts.
# Use fuser -n tcp <port id> for tcp ports to see which process is using
# the port.
# For example to see which application is already using port 80 use:
$ fuser -n tcp 80
# The netstat command can also be used to determine what process is using
# a port.
# Use netstat -nlp and you should see PID and names of programs along with
# the port they are using (note you can only see the PID of process you
# own, unless running as root)
$ netstat -p