Re: Clarification needed on signal spec EXIT

[Francis Moreau]

On Tue, Oct 16, 2012 at 10:00 PM, Bob Proulx <bob@proulx.com> wrote:
> Francis Moreau wrote:
>> --------------
>> main_cleanup () { echo main cleanup; }
>> submain_cleanup () { echo sub cleanup; }
>>
>> trap main_cleanup EXIT
>>
>> task_in_background () {
>>         echo "subshell $BASHPID"
>>
>>         while :; do
>>                 # echo "FOO"
>>                 sleep 1
>>         done
>>         echo "subshell exiting..."
>> }
>>
>> {
>>         trap submain_cleanup EXIT
>>         trap
>>         task_in_background
>> } &
>>
>> echo exiting...
>> --------------
>>
>> Sending TERM signal to the subshell doesn't make "submain_cleanup()"
>> to be called.
>
> And it does in ksh93.  Hmm...  And it does if I comment out the line
> "trap main_cleanup EXIT".  It seems to only set the trap if no trap
> handler was previously set.

Yes that's right.

Even weirder: if the subshell exits by calling "exit 1", then the trap
handler is not called at all regardless of whether or not the "trap
main_cleanup EXIT" is commented you.

To make that case work, you need to use the "( ... ) &" construct
instead of "{ ... } &" one.

This is why I was asking for clarification :)
-- 
Francis