mjhjmtu

From Bash manual

If Bash is waiting for a command to complete and receives a signal for
which a trap has been set, the trap will not be executed until the
command completes.

When Bash is waiting for an asynchronous command via the wait builtin,
the reception of a signal for which a trap has been set will cause the
wait builtin to return immediately with an exit status greater than
128, immediately after which the trap is executed.

I created some experiments for the first sentence.

1. 
   

   In a shell running in a tab in lxterminal:

   
   
   

   $ trap "echo hello" HUP
   $ sleep 100
   

   
   
   

   I then close the tab window, so that send SIGHUP to the shell.

   
   
   

   The shell exits immediately, instead of waiting for sleep 100 to
   complete, and then executing the trap. I was wondering why? Did I
   miss something?

   
   


2. 
   

   This one works

   
   
   

   $ trap -p
   trap -- 'echo hello' SIGHUP
   $ echo $$
   19708
   $ sleep 100
   

   
   
   

   Then run from another tab of lxterminal:

   
   
   

   $ kill -HUP 19708
   $
   

   
   
   

   When the sleep command in the first tab completes:

   
   
   

   $ sleep 100
   hello
   

   
   

Thanks.

Related When typing ctrl-c in a terminal, why isn't the foreground job terminated until it completes?