help!! can someone please explain me this script

i m no good in scripting.
the source is here
*www.idevelopment.info/data/Unix/Li...html#Configure iSCSI Initiator and New Volume

and the code is here

Code:

/etc/udev/scripts/iscsidev.sh

#!/bin/sh

# FILE: /etc/udev/scripts/iscsidev.sh

BUS=${1}
HOST=${BUS%%:*}

[ -e /sys/class/iscsi_host ] || exit 1

file="/sys/class/iscsi_host/host${HOST}/device/session*/iscsi_session*/targetname"

target_name=$(cat ${file})

# This is not an open-scsi drive
if [ -z "${target_name}" ]; then
   exit 1
fi

echo "${target_name##*.}"

for the time being i need ur help in understanding this.
spoon feeding apart .. plz direct me to a place where i can understand scripting. i know there are scores on the net. any good tutorial which you folks may v used.

thanks

Bash scripting
*tldp.org/LDP/abs/html/

I think tldp is enough for the start.

thank you ....