I was reading a blog post the other day (sorry, lost the URL...), it gives a pretty cool optimization in for loop;

In stead of:

for ($i < 0; $i < count($array_X); $i++) {

  // do something....

}

One can do this and only one count() is executed:

for ($i < 0, $cnt = count($array_X); $i < $cnt; $i++) {

  // do something....

}

I alright has a little concern when I put in that count(), or whatever expensive operation in the evaluation. But never think of this trick, even I know about I can initialize more than one value in a loop.

My home network always has local domain setup so I can ssh to admun2 instead of 192.168.0.x.

This is achieved by running a bind server w/ DNS forwarding, and a local domain served by bind. This works and provide a mean for me to learn about setting DNS domain in a small network.

But this time around when I move my server setup to CentOS 5, I read about dnsmasq. After some research, it seems this provides the function I setup w/ bind, but much easier to configure!

1) install (or ensure) dnsmasq: yum install dnsmasq
2) start the server: /etc/init.d/dnsmasq start
3) setup server to start on boot-up: chkconfig --level 345 dnsmasq on
4) ensure DNS port (TCP port 53) is unblocked in the firewall
5) setup /etc/hosts with local domain IP/hostname i.e. 192.168.0.99 admun2
6) set dnsmasq server IP as primary DNS in DSL router's DHCP setting

I never really done much of math in shell script in the past, but a script that collect logs recently require some simple add up.

#!/bin/sh

x=1;

y=2;

echo $((x+y));