From: Adrian Roskrow <adrian@...10systems.co.uk>
Date: 2007-01-19T04:51:25+09:00
Subject: Re: Reading from $stdin

Hi

I must be really stupid but I don't understand this at all, How does the 
usb scanner  connect, to a text editor. I don't know how to do that. I 
understand how the scanner reads one line at a time, the end of the line 
being \r\n. What prompts the scanner to read another line, does the \r 
or \n do it? Barcode reader driver? there is no driver, have I got to 
write one?

Adrian

Martin Portman wrote:
> Adrian Roskrow wrote:
>> Well I have written a small script to read from stdin and guess what, it 
>> just sits and does nothing!! I guess I must of got it wrong! Here is 
>> small snip-it
>>    @number = $stdin.each_with_index do |line, index|
>>         printf "%4d %s", index, line
>>         end
>> 
> 
> each_with index reads one line at a time.  A line needs to be
> terminated with an end of line character(s) before it can be read.
> 
> Does your barcode reader insert end of line characters(s) at the end
> of the content of the barcode?
> 
> I've used a usb barcode reader (in windows xp) and it does insert
> \r\n on the end of each sucessful read.  Try the reader out in
> a text editor to see if it does.    If it doesn't, you'll need to
> adopt a different approach than reading lines.  Alternatively
> in the barcode driver, there may be an option to force it to emit
> end of line characters.
> 
> If the barcode reader inserts chars into the editor, just like a 
> keyboard,
> you shouldn't need to redirect the input at all.  It should
> appear on $stdin.
> 
> Martin.


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