xiluhua@localhost ~/tscripts $ echo "hello world !"-bash: !": event not foundxiluhua@localhost ~/tscripts $ echo ‘hello world !‘hello world !xiluhua@localhost ~/tscripts $ echo ‘hello world !‘ >> t1.sh xiluhua@localhost ~/tscripts $ cat t1.sh #!/bin/bashhello 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 $