From: Todd Holloway <todd@...>
Date: 2002-07-04T05:27:00+09:00
Subject: ruby and 8192 bytes

The following code produces a 8192 byte file on machine2,
using both ruby 1.6.7 and 1.7.2. 

I have tried just using the "system" commands by themselves
and they seem to work just fine. I have also tried removing
the "system" commands and the local file is not shortened
to 8192 bytes. So, something is getting corrupted in between.

I think it might be a file open/close issue, but since
this is my first "real" ruby program...I'm not having
luck figuring it out. If it matters the correct
file size is: 9579 bytes...at least with the current
iptables rules and subsitutions.

I thought it was my bad regexs...but thanks to Matz
and many others I got that part correct. :)

thanks as always,
todd




#!/usr/local/bin/ruby -w

# this Ruby program takes the /etc/sysconfig/iptables from "machine1"
# and creates an appropriate one for "machine2"

# adds File.["compare", "move", "safe_unlink", "o_chmod", "mv",
# "makedirs", "cp", "cmp", "mkpath", "syscopy", "rm_f",
# "copy", "install", "catname"]
require 'ftools'
#
## in-line editting w/o a backup copy
$-i  = ""
#
## Change current working
Dir.chdir("/etc/sysconfig")
#
begin
# copy iptables to iptables4machine2 and report any errors
File.copy("iptables","iptables4machine2",true)
   rescue SystemCallError
    $stderr.print "Copy failed: " + $! + "\n"
    raise
end

# Replace any command line arguments with iptables4machine2
begin
# Replace any command line arguments with iptables4machine2
ARGV.replace(['iptables4machine2'])

  while line = gets
    next if /^\s*#/ =~ line
    next if /^\s*$/ =~ line

    # perform substitution in place
    # changes "machine1" external IP address "machine2"
    line.gsub!(/10.1.0.1/,'10.1.0.2')
    # changes "machine1" internal IP address "machine2"
    line.gsub!(/192.168.1.1/,'192.168.1.2')
    print line.gsub(/-A INPUT -s 192.168.1.2 -p icmp -m state --state NEW/,
                    '-A INPUT -s 192.168.1.1 -p icmp -m state --state NEW')
    end

    rescue SystemCallError
    $stderr.print "Something failed: " + $! + "\n"
    File.delete("iptables4machine2")
    raise
end


system("ssh machine2 cp /etc/sysconfig/iptables /etc/sysconfig/iptables.orig")
system("scp iptables4machine2 machine2:/etc/sysconfig/iptables")
system("ssh machine2 /etc/init.d/iptables stop")
system("ssh machine2 /etc/init.d/iptables start")