Re: PATCH: Util/helpfiles failing on old-fashioned unix

[Martin Vaeth <vaeth@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

Wayne Davison <wayned@xxxxxxxxxxxxxxxxxxxxx> wrote:
> vaeth@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
>> Unfortunately, I do not know a way in perl to redirect stdin *and* stdout
>> of a subprocess simultaneously.
>>
>
> One easy way is to use IPC::Open3 <http://perldoc.perl.org/IPC/Open3.html>,
> which is a default library that comes with perl.  This lets you start a
> subprocess with any desired stdin & stdout & stderr.

Thanks. However, from the avoidance of the perl5 keyword "my" in
Util/helpfiles (and falling back to e.g. local) I guess that this
script is supposed to run even on historical perl{3,4} variants
where libraries can hardly be expected.
Looking at the implementation of IPC::Open3, I see that everything
is setup manually using e.g. "pipe" and "fork". The latter,
unsurprisingly, is not implemented on all systems.

Summarizing, I think that the posted solution with tempfiles is
more compatible, since its "system" call should work even in
non-multitasking environments (and does not need a cumbersome
implementation to make it work with historical perl variants).
It was intentional that the implementation used no library
(neither File::Temp::tempfile to produce the temporary file nor
File::Spec::catfile to concatenate directory and filename).
I even refrained from quoting the directories (hence, spaces
in the "help" directory name would cause trouble) to not rely
too much on the underlying shell used by perl.