From: Robert Klemme <shortcutter@...>
Date: 2010-09-27T05:00:13+09:00
Subject: Re: mixing string formatting with system exec

On 26.09.2010 21:26, Nate St.Germain wrote:
> noob question…
>
> why does this line produce the following result?
>
> %x("%s %s" % ['/usr/bin/touch', '/tmp/test'])
>
> error:
> sh: line 0: fg: no job control
>
> i don't necessarily need to use string formatting or substitution here,
> just curious about the result.
>
> thanks.

%x is backticks and the contents between brackets are passed unmodified 
to the shell:

Robert@babelfish ~
$ ruby19 -e 'p %x[ls a]'
ls: cannot access a: No such file or directory
""

Robert@babelfish ~
$ ruby19 -e 'p %x["ls a"]'
sh: ls a: command not found
""

You are essentially doing the same as this:

irb(main):002:0> system '"%s %s" % [\'/usr/bin/touch\', \'/tmp/test\']'
sh: line 0: fg: no job control
=> false

You get the same if you call bash as sh directly:

Robert@babelfish ~
$ /bin/sh -c '"%s %s"'
/bin/sh: line 0: fg: no job control


Kind regards

	robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/