VirtualBox makes it easy to run virtual environments on your Ubuntu machine.  You can add a launcher to your desktop to make accessing your virtual machine even easier.  Here’s how:

1. Right-click your desktop and select Create Launcher from the context menu.

2. From the Create Launcher window, keep the Type as Application.  In the Name textbox, input the name that will be used to label the launcher.  In the Command textbox, input the following:

VBoxManage startvm your_virtual_machine_name

making sure to use the name of your Virtual Machine as it is labeled in VirtualBox.

3. Click OK.

The launcher will be placed on your desktop, giving you instant access to your virtual machine.

A very useful tool in any kind of troubleshooting is checking out the log files. Whether you’re troubleshooting a system problem, monitoring a mail server or simply checking the visitors for a web server the log files are your best friend. There are a few ways to handle this.

Probably the most common command used to keep an eye on log files is tail. Here are a few examples:

tail -f /var/log/syslog

tail -n25 /var/log/mail.log

tail -F /var/log/lighttpd/error.log

You’ll notice that each command above used a different option. Let me explain what each does.

-f, –follow : output appended data as the file grows

-n, –lines: output the last N lines, instead of the last 10; or use +N to output lines starting with the Nth

-F: same as –follow –retry

–retry: keep trying to open a file even if it is inaccessible when tail starts or if it becomes inaccessible later

Also note that ctrl-c will stop the -f or –follow options.

One thing that I’ve learned in all my troubleshooting and administration is that the system almost always tells you what the problem is. The trick is to simply know where to look. /var/log/messages, /var/log/syslog and other files in the /var/log/ directory will almost surely have the answer.

With the release of Ubuntu 9.04 (Jaunty Jackalope) it is time to dust off the tweaks I perform with each new version.

I have a few RaLink rt2500 based wireless (wifi) pci adapters from MSI . One issue I tweak for is well known and is due to the way the driver is initialised in the kernel at 1Mb/s instead of 54Mb/s.

The other problem is related to suspend. It is nice to see that suspend and resume is working so well in Jaunty. Unfortunately the rt2500pci doesn’t seem to wake up after resuming from suspend.

It appears that there is an easy solution for the rt2500pci or the hard way. The easy solution is to install linux-backports-modules-jaunty (sudo apt-get install linux-backports-modules-jaunty).

Problems solved.

The more difficult (not recommended) methods:

1) The old solution for the network connection speed was to type the following in the terminal:

sudo gedit /etc/rc.local

and add the line:

/sbin/iwconfig wlan0 rate 54M

Make sure it is before “exit 0″ and save it. After the next restart it should be operating at full speed. To make it happen sooner than after the next restart you can run this command in your favourite terminal:

sudo /sbin/iwconfig wlan0 rate 54M

and then uncheck and recheck “wireless networking” in the Network Manager Applet.

2) The old solution for suspend/resume was to add a file to the /etc/pm/config.d directory:

sudo gedit /etc/pm/config.d/rt2500pci

and add the line:

SUSPEND_MODULES="rt2500pci"

The file name can be whatever you want it to be but go ahead and save it and then after the next restart it should wake from suspend properly.

I use a one terabyte external hard drive for backing up data. The drive came formatted with a FAT filesystem, which I immediately replaced with the more reliable ext3. After formatting the drive as ext3 I noticed that the storage capacity had dropped considerably.

Why did this happen? Linux filesystems such as ext3 reserve a percentage of their capacity for privileged processes. In the case that the filesystem fills up, important processes with be able to continue functioning and writing to the disk.

By default 5% of a filesystem will be reserved. For modern high-capacity disks, this is much higher than necessary. On my 1 TB disk, this 5% works out to be 50 GB! If you’ve got a large filesystem, or a filesystem which does not store your Linux system files, it’s safe to reduce the percentage of reserved blocks to free up that disk space.

Use the tune2fs utility to do this. The command below would set the percentage of reserved blocks on the partition /dev/sdf1 to 1%:
sudo tune2fs -m 1 /dev/sdf1

Be sure to replace /dev/sdf1 with your own path; you can use the df command to get a listing of your filesystem device paths and their mount points.

I freed 37 GB of space by changing the reserved blocks to 1% on my TB drive.

So I’ve taken a small break break from posting about the web server to post a few goodies concerning iPhone hacks. The other day, I jailbroke my iPhone with the primary motivation of tethering the 3G connection to my EEE PC running Ubuntu 8.10. Currently, there is no tethering plan available from AT&T,  however tethering via this hack is a violation of your usage agreement. I have posted about a similar process with Verizon, but that hack has recently been disabled.

Install PdaNet

First, you must jailbreak your iPhone (room here for a whole new post). Install PdaNet through Cydia or installer. It should show up using just the default repositories. PdaNet will let you tether via Wifi to any platform or via USB to Windows. It is free to use for web traffic, but a $29 licence is required to use other web functions (ie- ssh, ftp, instant messaging, etc.). The full version will function for 14 days after the installation, then it will switch to the free version if not registered.

Setup Tethering

Once PdaNet is installed, open it by tapping on its icon. Click Settings and change the mode to “WiFi Router Mode.” Now go to the Ubuntu machine and left click on the network manager applet icon in the notification area. Click “Create New Wireless Network.” In this article, I will call the network “eeenet” and set security to none, but you may set these to whatever you like. If the network does not connect correctly, don’t worry. Right click on the network manager applet icon and select “Edit Connections.” Go to the Wireless tab and edit eeenet. Check the box to Connect automatically, make sure the mode is set to Ad-hoc, and change the Method in the IPv4 Settings to Automatic (DHCP). Click Ok and close the Network Connections Box. Now, left click the network manager applet icon and you should be able to join eeenet. Click on it and it will try to join.

Now, open the iPhone and go to the Wifi Settings. You should now see eeenet. Join it. The iPhone should successfu...