Report when a foreground job is terminated by a signal

[magicant]

trafficstars

Some existing shells display a message when a foreground job terminates due to a signal. Like yash 2, yash-rs should also implement this behavior.

Questions:

• [ ] Should the message be displayed if the shell is non-interactive?
• [ ] Should the message be displayed if job control is off?
• [ ] What is the rationale for POSIX allowing this behavior?