From: Laurent Sansonetti <laurent@...>
Date: 2003-02-28T19:38:43+09:00
Subject: reading the output of a program "in real-time"

Hi Rubists ;-)

I'm still learning Ruby, and I have a small question.

Is there a way to read the output of a program "line by line", in 
real-time ?

I would like to execute CVSup and to display its output in a Gtk 
list-view component each time CVSup prints a line on $stdout.

I have experimented 3 tests: each one prints directly the output in one 
shot (this is *not* what I want) :

---

# TEST 1
IO.popen("./plok") { |pipe|
    pipe.each_line { |line|
        puts line
    }
}


# TEST 2
rd, wr = IO.pipe

fork {
     puts "child"
     $stdout = wr
     rd.close
     exec("./plok")
}

wr.close
puts "father = waiting for output"
while rd.gets do
     puts "==> #{$_}"
end

# TEST 3
IO.popen("./plok") { |ruby|
     while ruby.gets do
         puts("==> #{$_}")
     end
}

---

Thank you in advance (and excuse-me for my bad english),

--
Laurent