This script is a bash script that should work for OS X greater than or equal to Mavericks (10.9).
This script use AppleScript command "display notification"
Usage: notify [-t <Title>]
[-s <Subtitle>]
[-m <Message>]
[-a <Sound path>]
[- v (this is verbose mode)]
Example usage:
notify -t "Demo Title" -s "This is Subtitle" -m "I love this convenient script" -a "Basso.aiff"
Where .aiff available sound files names could be found in /System/Library/Sounds/
Notification popup does show AppleScript icon. It's not possible to customize this icon. Unless you create your own AppleScript bundle using your custom icon (see this thread). But in this case this convenient (very simple) script would not make much sens.