From: Michael Guterl <mguterl@...>
Date: 2008-10-20T02:31:38+09:00
Subject: Re: Error Exception if script doesn't run

On Sun, Oct 19, 2008 at 1:19 PM, jackster the jackle
<johnsheahan@sflistdb.com> wrote:
> Brian Candler wrote:
>> jackster the jackle wrote:
>>> $? equals 0, however if I change the path to js.txt to something that
>>> doesn't exist in order to make it fail, $? has a value of 256.
>>
>> That's because the low-order 8 bits of $? encode something different;
>> the next 7 bits are the exit code (0 to 127). Use $?.exitstatus to get
>> that.
>>
>> http://www.ruby-doc.org/core/classes/Process/Status.html
>>
>>> I thought $? should always have a value of 1 when it fails? Why is it
>>> 256?
>>
>> The exit status in this case is 256 >> 8, which is 1.
>
> this code seems to work well for what I need:
>
> `cp /xhome/jsmith/js.txt /home/jsmith/js2.txt`
> unless $?.success?; raise "error with: #{$0}" ; end
>
> I would like to be able to add the line number of the file into the
> error message with the file name ($0) but when I try other global
> variables such as $@ or $. I don't get the line number of the script
> that failed?
>
Look into __LINE__

HTH,
Michael Guterl