From: "Ara.T.Howard" <ahoward@...>
Date: 2004-04-28T08:24:03+09:00
Subject: Re: popen issues

On Wed, 28 Apr 2004, Kristof Bastiaensen wrote:

> Hi,
> 
> It is maybe not a good idea to use /bin/bash as a pipe, because it is an
> interactive interpreter, and not made for pipe-communication.  Normally you
> would just check for an end of file byte, but bash will not send you one.
> Is there any reason to use bash?

really?  mine does:

  ~ > ruby -e 'p IO.popen("bash -c exit").eof?'
  true

  ~ > uname -srm && bash --version
  uname -srm && bash --version
  Linux 2.4.20-30.73ncirt i686
  GNU bash, version 2.05a.0(1)-release (i686-pc-linux-gnu)
  Copyright 2001 Free Software Foundation, Inc.

how about you?

-a

> 
> 
> On Wed, 28 Apr 2004 06:06:30 +0900, Hal Fulton wrote:
> 
> > Here's something I've never figured out.
> > 
> > Suppose I want real two-way communication with a process via popen.
> > This seems doable.
> > 
> > But apparently the read hangs until I do a close_write; and if I
> > do that, I can't write again. A flush doesn't work.
> > 
> > Here's what I was thinking (simplified):
> > 
> >    io = IO.popen("/bin/bash","r+") do |f|
> >      f.puts "ls"
> >      puts f.readlines
> >      f.puts "date"
> >      puts f.readlines
> >    end
> > 
> > I even tried this (following) abomination, to no avail:
> > 
> >    io = IO.popen("/bin/bash","r+") do |f|
> >      writer = f.dup
> >      f.puts "ls\n"
> >      f.close_write
> >      puts f.readlines
> >      w = writer.dup
> >      w.puts "date\n"
> >      w.close_write
> >      puts f.readlines
> >    end
> > 
> > 
> > Can someone advise?
> > 
> > 
> > Hal
> 
> 

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