Bash String Manipulation

#!/bin/bash
#

# Extract File Extension
file_ext=${filename_or_path##*.}

# Extract File Name From Full Path
# This returns the file name given a full path:
file_name=${full_path_var##*/}

# This returns the file name for the currently running bash script:
script_name=${0##*/}

# This returns the directory path for a given full file path:
dir_path=${full_file_path%/*}