Get script's own directory in bash script

It was always a problem for me to get the directory the called script is stored in, in the script itself. Thanks to this SO question (http://stackoverflow.com/questions/59895/can-a-bash-script-tell-what-directory-its-stored-in) it's not a problem anymore. As it says:

DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"

Or, to get the dereferenced path (all directory symlinks resolved), do this:

DIR="$( cd -P "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"

Get specific PC IP from "arp -a"

I want to extract IP of machine leonidas. arp -a returns such line (among others): 
leonidas.home (192.168.1.5) at 0:1c:c0:de:8f:28 on en1 ifscope [ethernet] 

To have only IP:
arp -a | grep leonidas | cut -f 2 -d ' ' | sed 's/[()]//g'
prints
192.168.1.5