By default, VirtualBox only allows to install 32 bit OS on it. But sometimes, 64 bit OS is wanted for specific uses such as running platform specific tests. To allow installing 64 bit OS on VirtualBox. Below information is needed.Here is the official documentation about 64 bit OS:VirtualBox supports 64-bit guest operating systems, even on 32-bit host operating systems, provided that the following conditions are met:You need a 64-bit processor with hardware virtualization support (see the section called “Hardware vs. software virtualization”).You must enable hardware virtualization ...

These two days, I am building a website and deploying it on a VPS server which uses CentOS 5. I don't have cPanel or Plesk for my account, so I need to install and configure everything myself including Apache, PHP, MySQL and FTP server, also today's topic cron job. Since my website has a ranking algorithm to calculate the rankings of each link and update the ranking on database and I need to calculate the rankings every 5 minutes, so I think to use cron jobs. Here are what I have done which may help you.First we need to understand the crontab commands, it can have different options with this c...

As a system administrator or network engineer or application developer, there is a need to check whether a port on remote server is open so that you can tell whether the service under check is running or not. In this post, we would cover a few methods to check whether a remote server port is open or not on Linux.telnettelnet is the most frequently used command on both Windows and Linux to check port. The simple usage for this command is telnet [host] [port]When the port is open, the output will be like:Trying 192.168.56.160...Connected to 192.168.56.160.Escape character is '^]'.SSH-2.0-Op...

Browser war among major browsers is continuing for a long time since last century. Just a few years ago, Internet Explorer was the most used web browser. But now the situation is completely different, people are making fun of Internet Explorer and switching to other browsers. Today we share some jokes about Internet Explorer, it's just for fun, so grab a cup of coffee and sit down and enjoy.Hmm, is IE so slow?What gun is it?Hmm, I am still one step behindAnd I am lost.Hey, what is HTML5?I am on my own.Are parents still using this?Am I wrong? Everyone wants to be the default web browser.All ima...

Last week I was generating a MD5 sum for an virtual machine image on one OpenNebula server:# ls -l test.img-rw-r--r-- 1 root root 10486808576 Oct 12 02:21 test.img# md5sum test.imgAt the same time I was clearing the files on the server on another terminal and deleted the above image file mistakenly with :# rm test.imgSince this image file is 10GB, it took some time to remove this file from the server, so I used the Ctrl+Z command to suspend the remove command.[1]+ Stopped md5sum test.imgBy doing this, we can recover the deleted image file later. The rationale here is if other ...

Summary: Mark Shuttleworth says yes, Ubuntu is now competitive with Red Hat Enterprise Linux in the enterprise space. Since last summer, Ubuntu has been more popular than Red Hat as a Web server.When you think of Ubuntu Linux, what do you think of? I would guess you think about the Linux desktop. While Ubuntu is certainly a big player—maybe the biggest—when it comes to the Linux desktop, Mark Shuttleworth, founder of Canonical, the company behind Ubuntu wants you to know that “A remarkable thing happened this year: companies started ...

Windows 7 is another great operating system released by Microsoft after Windows XP. Since Microsoft has announced that it suspended the support of Windows XP starting from April 8, 2014. Many users have been forced to move to Windows 7. Unfortunately, if you are using a bootable USB flash drive to install Windows 7 and your computer doesn't have USB 2.0 port but only USB 3.0 port, you will encounter missing driver issue while installing it. This post will show you how to workaround this issue.Before installing the Windows 7, we have to have below things ready:A flash drive with capacity not le...

There are many open source server monitoring software such as cacti and nagios. Besides these, can we write our own shell scripts to monitor them? The shell scripts written by ourselves can fulfill our special requirements better and have a more detailed coverage.Below are some commonly used shell scripts used by Evangelist, an Oracle DBA. 1. Check network gateway traffic#!/bin/bash#network#Mike.Xuwhile : ; do time='date +%m"-"%d" "%k":"%M' day='date +%m"-"%d' rx_before='ifconfig eth0|sed -n "8"p|awk '{print $2}'|cut -c7-' tx_before='ifconfig eth0|sed -n "8"p|awk '{print $6...