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My rakefile needs to abort when an html
file can't be parsed into REXML, so I
can report the error and fix it. But...

Running tidy in a subshell, I can find
no way to access the error message it
sends to std error. I can see it, but
is there a way to get ruby to see it?

This idiom doesn't seem to work

sh "tidy ... > file" do |ok, res|
if !ok then
# Never runs
end
end

The "result" is an empty string. Std out
goes to the file, as expected, but std
error does not go to res.

Trying to run htree instead, I have some
strange ".so not found" error that I
posted last week, but am unable to decipher
on my own. (Of necessity, ruby is in a
non-standard location, and that seems to be
causing difficulties.)

I need a workaround, or a different strategy.

On Jul 17, 2006, at 11:39 PM, Eric Armstrong wrote:
> Running tidy in a subshell, I can find
> no way to access the error message it
> sends to std error. I can see it, but
> is there a way to get ruby to see it?
>
> This idiom doesn't seem to work
>
> sh "tidy ... > file" do |ok, res|
> if !ok then
> # Never runs
> end
> end

You can redirect stderr to a file:

tidy ... > file 2> errlog

Maybe that will get you going in the right direction.

Eric Armstrong wrote:
> My rakefile needs to abort when an html
> file can't be parsed into REXML, so I
> can report the error and fix it. But...
>
> Running tidy in a subshell, I can find
> no way to access the error message it
> sends to std error. I can see it, but
> is there a way to get ruby to see it?
You can:

- Use open3, which gives you access to stderr.
(http://ruby-doc.org/stdlib/libdoc/open3/rdoc/index.html)

- Use ruby-tidy, which wraps the tidy library and gives you exceptions
when things go wrong. (http://rubyforge.org/projects/tidy)

- Redirect stderr in your shell command. ("tidy ... > file 2> errors")

I've used the second method quite successfully. It's dead simple, but
you've got to be careful about different Ruby threads using the library.
It's quite easy to make it go pop unless you wrap it in a critical
section.

--
Alex

Thanks, Alex. And you, too, "gwtmp01".
Cripes. I never knew about "2>"! That's
the easiest solution, in this case.

I appreciate the additional information,
as well. They give me some alternatives
to examine.

You guys saved the day! Thanks much.

Alex Young wrote:
> Eric Armstrong wrote:
>> My rakefile needs to abort when an html
>> file can't be parsed into REXML, so I
>> can report the error and fix it. But...
>>
>> Running tidy in a subshell, I can find
>> no way to access the error message it
>> sends to std error. I can see it, but
>> is there a way to get ruby to see it?
> You can:
>
> - Use open3, which gives you access to stderr.
> (http://ruby-doc.org/stdlib/libdoc/open3/rdoc/index.html)
>
> - Use ruby-tidy, which wraps the tidy library and gives you exceptions
> when things go wrong. (http://rubyforge.org/projects/tidy)
>
> - Redirect stderr in your shell command. ("tidy ... > file 2> errors")
>
> I've used the second method quite successfully. It's dead simple, but
> you've got to be careful about different Ruby threads using the library.
> It's quite easy to make it go pop unless you wrap it in a critical
> section.
>