From: Josh Cheek <josh.cheek@...>
Date: 2010-07-02T09:02:13+09:00
Subject: Re: Running a shell command from ruby

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On Thu, Jul 1, 2010 at 2:53 PM, Steve Pauly <stevepauly@comcast.net> wrote:

> I am experimenting with running bash commands from within ruby. The
> commands should be in an array, separated internally with semicolons.
>
> The problem is that they do not get executed.
>
> My script:
>
> ----
> #!/usr/bin/ruby
> script1=["touch ~/ruby/f1;touch ~/ruby/f2"]    #addl array elements to
> be added
> puts script1[0].split(/;/) do |k|
>  puts k
>  system(k)
> end
> ----
>
> The output from "puts k" looks good.
> But why do the files f1 and f2 not get created?
>
> I realize that executing commands this way in ruby may be bad practise,
> but at least, why do the commands not execute?
>
> Thanks in advance.
> Steve.
> --
> Posted via http://www.ruby-forum.com/.
>
>

It has to do with block bindings. do ... end bind to the furthest left
method call on the line, so in this case, the block is being passed to the
puts method, not the split method.



def puts( *args , &block )
  super "puts received: #{args.inspect}, and #{block ? 'a' : 'no'} block."
end

script1=["touch ~/ruby/f1;touch ~/ruby/f2"]    #addl array elements to be
added
puts script1[0].split(/;/) do |k|
 puts k
 system(k)
end

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