Friday, June 27, 2008

How to change the background of Speed Dial in Opera 9.50


Updated 2 September 2008:
To change the background of the Speed Dial tab in Opera 9.50, you need to do the following:
  1. Go to Tools --> Appearance --> Skin to find out which skin you are using. If it says Opera Standard, you are using the default skin, otherwise, you are using a downloaded skin. Note the name of the skin.
  2. As root, open the zip-file containing the Opera skin that you are using. The default skin can be found at /usr/share/opera/skin/standard_skin.zip, while downloaded skins can be found at /home/username/.opera/skin/*.zip. You can use the following command in a terminal:
    sudo gnome-open /usr/share/opera/skin/standard_skin.zip
  3. Open the folder /backgrounds in the zip-file by double-clicking it.
  4. Open a file browser (Nautilus) and locate a background image that you want to use, e.g., /usr/share/wallpapers/triplegears.jpg.
  5. Add the background image (triplegears.jpg) to the /backgrounds folder by pressing the Add Files... button and locating the image.
  6. Open skin.ini from the zip-file and scroll down, or use Ctrl+F, to go to the line containing
    [Speed Dial Widget Skin]
    Underneath this heading, add 
    Type = BoxTile
    Tile Center = backgrounds/triplegears.jpg
  7. Save skin.ini inside the zip-file, click "yes" to update the  archive, and restart the browser.

Note that your newly installed background image for the Speed Dial tab may be affected by the current color scheme. In my case, the background image became very bluish because the color scheme was set to system colors. To avoid this, go to Appearance (Shift+F12) and make sure Color Scheme is set to No color scheme.

Some screenshots:

1. Determine the skin you are currently using:

2. The zip-file containing the skin:

3. The /backgrounds folder in the zip-file (note Add Files button):

4. Locating a suitable background image using Nautilus:

5. Click Add Files in the /backgrounds folder (see 3. above) and  add the background image:

6. Edit the file skin.ini to use the background image by adding the two lines in blue:

7. Save skin.ini and click "Yes" to update archive:

Add more speed dials and remove search field in Opera 9.50

By default, Opera 9.50 comes with 9 speed dials when you open a new tab. However, you may have a screen size and resolution that would accomodate more speed dials. For example, to get 4 x 3 speed dials, do the following:

  1. Go to Help → About Opera and note the path of your main Opera directory (look for the opera6.ini file), usually /home/username/.opera/.
  2. Make sure Opera is not running, then open speeddial.ini from this directory and add the following three lines:
    [Size]
    Rows=4
    Columns=3
  3. Start Opera and note the change.
You can still open the 9 first speed dials using Ctrl+n, where n=1-9. To add shortcuts to the other speed dials, follow this guide.

To get some extra space, you can turn off the search field the top of the Speed Dial page. Enter opera:config#UserPrefs|SpeedDialSearchType in the address field, hit Enter, and replace the value with 0. Scroll down to the bottom and click Save.  The changes will take effect immediately without restart.

Thursday, June 26, 2008

Using Linux to scan and remove viruses from a Windows computer

A common problem with viruses is that they are often extremely difficult to remove. Most of the time, you easily understand that there is something strange about your Windows box (apart from the usual Windows behaviour, that is :D) , so you run a virus scan and indeed, confirm your worry that you have been infected. But what is the worth of your antivirus application if it is unable to remove the virus, not to mention detect it in the first place?! Often, you need to find a dedicated mini-application that removes a particular virus, but if you can't, you're screwed.

The following is a recipe that works:
1. Install Ubuntu 8.04 (Hardy Heron) Persistent on a USB stick (see this guide, and read my reasons why)
2.Install antivirus applications on the Ubuntu system on the USB stick.
  • Avast Antivirus is easy to install (.deb available) and is free but requires email registration for a key (no spam).
  • Clam Antivirus is free and also available from repositories (enable universe). If you prefer a graphical user interface (GUI), also install clamtk using Synaptic.
  • AVG Anti-Virus Free for Linux/Freebsd 7.5.50 is not their latest release but might do the job.
  • Trend Micro HouseCall is a free online scanning service. Linux distributions must support libc6.
3. Make sure the antivirus applications and virus definitions are all updated.
4. Boot up Ubuntu on the infected Windows computer using your USB stick. You may have to enter the BIOS setup to change the boot order to boot from USB before booting from the (Windows) hard drive.
5. Launch an antivirus application in Ubuntu and tell it to scan the directory /media, where the windows partitions shall have been automounted as /media/disk, /media/disk-1, etc. at boot time.

(Note: I have only tried Avast and Clam. I noted that Clam seemed to be unresponsive upon starting a scan, but after 30 seconds or so started scanning.)

When you have successfully cleaned your mom's/dad's/friend's computer, lend them your USB stick (with all the usual snacks like Compiz Fusion/the 3D cube, OpenOffice, Opera 9.5 with email set up, Amarok, VLC player etc.) and tell them that anything they can accomplish in Windows (well, perhaps with the exception of premium video editing suites such as Adobe Premiere Pro) they can do with free software in a virusfree Linux environment!

Why you should install Ubuntu 8.04 (Hardy Heron) Persistent on a USB stick

There are several reasons you should install Ubuntu on a USB flash drive. First of all, a USB memory stick is easier to bring around than a Live CD if you need to install Ubuntu on a computer. But more importantly, by installing the persistent version, not only can you use your USB as a Live CD, but in addition, you can save any changes to the system to disk! In effect, this means that you have your own portable system that you can bring anywhere. Forget the worry of bringing your valuable laptop on vacation. Instead, once you have booted your system onto somebody else's computer, you can install software, perform system upgrades, and do your work on your own customized system with your own software installed. Everything you do is saved onto your USB stick. And if you do need to access or save something on the underlying system, the computer hard drives will be automounted at startup.

Naturally, your system will be limited by the disk size of your USB. Most installations use about 700 MB (the size of a Live CD) for the Live portion of the system, leaving the rest of the disk as free space. With a dirt-cheap 4 or 8 GB USB stick, you have plenty of space to install software and files.

Running a system from a USB can also be convenient if you need dedicated servers to perform exactly what you want. Rather than going through a procedure of installing necessary software and making sure that everything works on the existing system, which likely is a Windows computer loaded with crap, you simply plug in your pre-prepared USB stick and boot from it. It is cheap and quick to buy 10 USB sticks, prepare the system and software on one of them, and then replicate the entire system onto the 9 others.

Another great usage is for removal of viruses on a Windows system. Viruses are often hard to get rid of, as they might get loaded during boot-up and refuse to be deleted by the Windows antivirus application. Booting Ubuntu from the USB and running a virus scanner such as Avast or Clam (Clam is also available from repositories) should enable you to remove the viruses. See my guide for further instructions.

So how do you make such a USB stick? I just followed this guide, which was a piece of cake. If you want the USB stick to also work as a normal flash drive when connected to a computer, you might want to add a third partition in addition to the two needed for the Ubuntu Persistent system. Format it as NTFS so it is readable on both Windows and Linux systems. You might need to have this partition as the first partition for Windows to discover it. I have not tried this myself, but believe it should work.

How to synchronise files with rsync

Everyone knows it is a good idea to backup your data. However, the good ol' copy'n'paste routine is time consuming, inefficient, and prone to errors. By using rsync, you can achieve efficient synchronisation of files as only the change in data will be transferred.

For example, you might want to synchronise your home directory, /home/username/, to your external hard drive, /media/externalhdd/homebackup/. A oneliner is all that is needed:
rsync -ra --progress --stats --log-file=rsynclog /home/username/ /media/externalhdd/homebackup
The options used are:
  • -r recursive (includes subfolders)
  • -a archive (preserves, ownership, timestamps, etc.)
  • --progress (shows progress of files being synchronised)
  • --stats (print some statistics after synchronisation)
  • --log-file=rsynclog (save useful information in file rsynclog in current directory)
For other options, do
rsync --help
You can also use rsync for synchronisation to remote servers. If so, you may do
rsync -ra --progress --size-only /home/username/ server.example.com:/home/username/homebackup/
Note that such a connection to a remote server is insecure! You should be using SSH. Google it to find out how. One possible starting point is here.

Finally, you may want to use a script that runs at scheduled times to automate your backup process. An example script can be downloaded here (see below). Modify the script by removing the user input and use cron to run it at regular times, e.g., every night. rsyncbackup.sh