From: kim jun young <juneng603@...>
Date: 2009-04-19T16:48:31+09:00
Subject: using pipe, but subprocess didn't flush.

hi, all,

I wanna to execute subprocess and catch subprocess' output from a pipe  
in a parent process.

but, unfortunately, a subprocess didn't flush it's output in stdout.  
As a result, the parent process cannot recognize what the subprocess  
did.

this is a sample code for my case.

clue 1) when I executed "isql -Usybase -P -SHOME_SERVER"

the first prompt of it is

1>

clue 2) in my program, I executed this.
read = IO.popen("isql -Usybase -P -SHOME_SERVER", "r")

puts read.sysread(2)

read.close

also it printout "1>"

clue 3) different case of clue 2
read = IO.popen("isql -Usybase -P -SHOME_SERVER", "r+") # read-write  
mode

puts read.sysread(2)

read.close

it doesn't print out anything.

clue 4) different case of clue 2
require "open3"
include Open3

stdin, stdout, stderr = popen3("isql -Usybase -P -SHOME_SERVER")

puts stdout.sysread(1) <-- wait forever.

could you suggest me solution?