From: Charlton <charlton.wang@...>
Date: 2006-12-21T15:40:05+09:00
Subject: Re: Kernel#system bug?

Hi Nobu,

Hm, I'm not sure I understand how this is natural. It's true that the
shell sets PWD but if I'm executing the same command from within a
Kernel#system call, I would have expected the directory context to be
consistent. If the directory viewed by the shell isn't coherent with
wherever I've taken ruby to (via Dir.chdir), then I would almost say
it's a busted implementation.

Cherers,
Charlton

Nobuyoshi Nakada wrote:
> Hi,
>
> At Thu, 21 Dec 2006 06:45:06 +0900,
> Charlton wrote in [ruby-talk:230639]:
> > Program:
> >
> > Dir.mkdir("bug") if !FileTest.exists?("bug")
> > File.open("bug/bugfile", "w") { |file|
> >     file << "Bug!"
> > }
> > Dir.chdir("bug")
> >
> > puts "without semi-colon"
> > IO.popen("env").readlines.each do |entry|
> >     puts entry if entry =~ /PWD/
> > end
> >
> > puts "with semi-colon"
> > IO.popen("env;").readlines.each do |entry|
> >     puts entry if entry =~ /PWD/
> > end
> >
> > Output:
> >
> > without semi-colon
> > PWD=/user/blah/tests/ruby
> > with semi-colon
> > PWD=/user/blah/tests/ruby/bug
>
> It is natural result.
> PWD is not set by OS automatically, but set by sh.
>
> You should use getcwd() in C or Dir.pwd in ruby instead of
> relying on $PWD.
> 
> -- 
> Nobu Nakada