From: "felix.leg" <felix.leg@...>
Date: 2010-10-08T03:40:14+09:00
Subject: popen hangs out for user input

Hi,

I want to use Ruby with latex,so I wrote a simple program which waits 
for "\typein" command called from pdflatex:

<CODE>
#!/usr/bin/ruby

file = IO.popen('pdflatex -interaction scrollmode test.tex','r+') #1

until file.readline.include? 'typein'; end
file.write "a line from RUBY"
file.readlines #2
file.close
</CODE>

If I run the command from #1 in a sheel it works right: scrolls 
"standard" latex asks, and stops for my "\@typein=". After I answer it 
continues normally.

But when I want do the same in Ruby with above code, it hangs out 
waiting for input. It looks like #2 causes this, but I don't know why...