Re: trap output piped to another program gives incomplete results

[Siddhesh Poyarekar]

On Sat, Apr 10, 2010 at 8:51 AM, Chet Ramey <chet.ramey@case.edu> wrote:
> On 3/31/10 1:45 AM, Siddhesh Poyarekar wrote:
>
>> Bash Version: 4.1
>> Patch Level: 2
>> Release Status: release
>>
>> Description:
>>               When output of trap is piped to another command, say, less or
>>               cat -, it shows only ignored signals.
>
> As the standard is currently written, this is the correct behavior.
>
> The standard considers traps in subshells in two places: where it talks
> about "subshell environments" and where it describes the behavior of trap.
>
> The former says only that all commands in a pipeline are run in a subshell
> environment, and that in a subshell environment traps "are set to the
> default values."  The latter says that "when a subshell is entered, traps
> that are not being ignored are set to the default actions."  This is an
> obvious contradiction, and most shells implement the latter.
>
> Bash and some other shells special-case command substitution, because the
> standard includes an example illustrating the use of command substitution
> to save and restore traps.  This is not univeral -- dash, for instance,
> does not do it.
>

Thanks, will you consider fixing this or accept a patch to fix this? A
fix along the lines of the standards change Eric pointed out ought to
work I think. I'm not sure at what point the change becomes
effective/enforceable.


-- 
Siddhesh Poyarekar
http://siddhesh.in