From: David Alan Black <dblack@...>
Date: 2002-07-23T03:27:31+09:00
Subject: Re: piping into ruby at command line

Hi --

On Tue, 23 Jul 2002, Dossy wrote:

> $ cat >junk.txt <<EOT
> asdf
> 1234
> EOT
>
> $ cat junk.txt | ruby -ne "print $_"
>
> Strangely, this didn't do what I expected:
>
> $ cat junk.txt | ruby -ne "puts $_"
>
> Using #puts, I got two blank lines.  This happens in both 1.6.7 and
> 1.7.2:
>
> ruby 1.6.7 (2002-03-19) [i386-linux]
> ruby 1.7.2 (2002-05-30) [i686-linux]

OK, after some mystification, I figured out what's happening.

The shell is interpolating its own $_ -- which is nothing.

So what you're really getting is just "print" and "puts".

print uses $_ (the Ruby one) by default.  puts doesn't.

Try putting the inline script in single quotes instead of double, or
escape the $ with a \ .


David

-- 
David Alan Black
home: dblack@candle.superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav