xiluhua@localhost ~/tscripts $ echo "hello world !"

-bash: !": event not found

xiluhua@localhost ~/tscripts $ echo 'hello world !'

hello world !

xiluhua@localhost ~/tscripts $ echo 'hello world !' >> t1.sh

xiluhua@localhost ~/tscripts $ cat t1.sh

#!/bin/bash

hello world !

xiluhua@localhost ~/tscripts $ vi t1.sh

xiluhua@localhost ~/tscripts $ chmod +x t1.sh

xiluhua@localhost ~/tscripts $ ./t1.sh

Hello world !

xiluhua@localhost ~/tscripts $ sh t1.sh

Hello world !

xiluhua@localhost ~/tscripts $ /bin/bash t1.sh

Hello world !

xiluhua@localhost ~/tscripts $