[Toybox] interesting new (?) env(1) options

[enh]

On Fri, Mar 15, 2024 at 2:22 PM Rob Landley <rob at landley.net> wrote:

> On 3/15/24 13:40, enh via Toybox wrote:
> > i've never noticed these before:
> >
> >        --block-signal[=SIG]
> >               block delivery of SIG signal(s) to COMMAND
> >
> >        --default-signal[=SIG]
> >               reset handling of SIG signal(s) to the default
> >
> >        --ignore-signal[=SIG]
> >               set handling of SIG signal(s) to do nothing
> >
> > i've not yet _needed_ them, but fyi in case anyone does. (the motivating
> example
> > in the man page is "making sure SIGPIPE actually works in a child,
> regardless of
> > the caller's signal disposition".)
>
> In 2011, I had an adventure, the punchline of which is here:
>
> https://landley.net/notes-2011.html#05-09-2011
>
> And the investigation leading up to it was:
>
> https://landley.net/notes-2011.html#24-08-2011
> https://landley.net/notes-2011.html#26-08-2011
> https://landley.net/notes-2011.html#28-08-2011
> https://landley.net/notes-2011.html#01-09-2011
> https://landley.net/notes-2011.html#02-09-2011
> https://landley.net/notes-2011.html#03-09-2011
> https://landley.net/notes-2011.html#04-09-2011
>
> tl;dr: autoconf was hanging in one of its tests, I safari'd through to the
> actual failure reproduction sequence then traced it THROUGH the kernel to
> eventually find an old bash bug (longjmp instead of siglongjmp) so when
> bash
> took a timeout trap it left SIGALRM blocked, and my PID 1 init script had a
> "read -t 3" that was doing that, meaning child processes that script
> started
> inherited the blocked SIGALRM, which didn't cause a problem until halfway
> through an autoconf build.
>
> That said, I'm not implementing --longopts without a short opt until
> somebody
> comes to me with a use case. And then I would come up with short options.
> Also,
> "env" is probably the wrong place to put this unless it's also going to
> sprout
> flags to change niceness level and so on: man 7 signal and man 7 environ
> are
> different pages.
>

i know what you mean, but at the same time, the fact that this swiss army
knife doesn't actually exist is a bug in its own right. i regularly find
people who don't realize which of these things there is/isn't a command
for. (because not only are they separate commands, even the man pages don't
generally refer to one another. because, like you say, in a sense they
_don't_ have anything much to do with one another.)


> Rob
>
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