John Rubinubi wrote:
> 
> Thanks. That did it. Here's another, no doubt equally stupid question.
> 
> On p. 16 of Programming Ruby is given
> 
> ARGF.each {|line| print line  if line =~/Ruby/ }
> 
> which is supposed to print the inputted lines which contain "Ruby"
> 
> The while loop example in the book runs as expected but this ARGF
> one-liner doesn't seem to do anything.
> 
> Thanks,
> 
> John

Now i know what ARGF is (after looking it up).  It's an alias for $< . .
. which means that it's the concatentation of the input files to your
program specified on the command line (or standard input if no files are
specified on command line).  Your one liner does work for me.  If you
don't specify any files on the command line, it reads from standard
input and echoes every line that you enter that contains "Ruby" in it. 
If you specify files on the command line, it will print only those lines
from those files that contain the word "Ruby".

craig