Re: EXIT trap in implicit vs. explicit pipeline subshell

[Miroslav Koskar]

On Jun 11 09:35, Chet Ramey wrote:
> On 6/11/15 4:08 AM, Miroslav Koskar wrote:
>
> > In fact group command { ... } would work too, as I've showed and you've
> > confirmed. One last bit here I guess, why is it that the $BASH_SUBSHELL,
> > would not reflect that is it in fact running in subshell?
>
> BASH_SUBSHELL measures (...) subshells, not pipeline elements.  For
> example, the following lines show that it has value `1':
>
> ( echo in subshell: $BASH_SUBSHELL )
> ( echo in subshell pipeline: $BASH_SUBSHELL ) | cat

Ok, I probably use term "subshell" too loosely, like everything running
in a separate process introducing separate shell environment. I'm sure
there are more nuances to that. Man page on pipeline explicitly states
that it is running parts in a subshell. That is true in that broader
sense, so maybe extending BASH_SUBSHELL man section to say it doesn't
apply for pipeline parts/elements then but only (...)?

But let's look at this:

{
  echo $BASH_SUBSHELL;
  trap 'echo EXIT-$$.$BASHPID.$BASH_SUBSHELL' EXIT
} | cat

Output:
1
EXIT-3706.3714.0

Is there an explanation and reason to not have BASH_SUBSHELL in above
case consistent? I've gathered that both should be 0, to be consistent
with above statements.

PS: Thanks for clarification on those other points in previous reply

Miro

--
Miroslav Koskar
http://mkoskar.com/

signature.asc
Description: PGP signature