Re: [Help-bash] When pipes fail (and when not)

[Eric Blake]

On 11/28/18 6:15 AM, Paul Wagner wrote:
> On 27.11.2018 19:03, Chet Ramey wrote:
> > If bash starts up with a signal ignored, you can't install a trap for 
> > it or
> > reset its disposition to SIG_DFL. You have to fix the problem at its 
> > root.
>
> Thanks for pointing that out.
>
> I still don't understand why setting the trap on a system that has 
> SIGPIPE vital doesn't work, so I'd be very greatful for any hints.

It's a lame restriction from POSIX based on historical practice (that I 
_really_ wish we weren't stuck with): 
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#trap

"Signals that were ignored on entry to a non-interactive shell cannot be 
trapped or reset, although no error need be reported when attempting to 
do so. An interactive shell may reset or catch signals ignored on entry. 
Traps shall remain in place for a given shell until explicitly changed 
with another trap command."

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
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