From bash manual
Non-builtin commands started by Bash have signal handlers set to the values inherited by the shell from its parent.
When job control is not in eff ect, asynchronous commands ignore SIGINT and SIGQUIT in addition to these inherited handlers.
Commands run as a result of command substitution ignore the keyboard-generated job control signals SIGTTIN, SIGTTOU, and SIGTSTP.
I was wondering if someone could give some examples to show what the above mean? Thanks.