Ubuntu. Simple backup that works.

UPDATE 10.08.2009, please read comment at foot of this post

Having recently been let down by mondorestore in Gutsy (see below) I have been researching a new backup strategy. I didn’t want to again leave myself trusting in a tool which lets you down when you really need it, so the stategy had to use readily available and trustworthy software. The solution I have decided upon and tested by doing a complete restore is as follows:

Backing up.
Firstly you need to copy your home directory using sudo grsync (preserve time, owner, permissions and group) or

sudo rsync -r -t -p -o -g -v --progress -l /home/ /media/disk/home/

Keep a copy of this somewhere so that you can find it when your system dies ie on an external drive. Sync it regularly, rsync will only update changes to the original so after the first copy has been made, updates usually only require a few seconds.

Then make a list of all of the packages in your installation using the command

sudo dpkg --get-selections | grep '[[:space:]]install$' | \awk '{print $1}' > package_list

Copy this file together with /etc/apt/sources.list to the same medium you have used for your /home/ directory backup.

You could initiate a cron job to keep this list up-to-date using by putting the following script in /etc/cron/dailypackage_list and making it executable.

#!/bin/sh
sudo dpkg --get-selections | grep '[[:space:]]install$' | \awk '{print $1}' > package_list

Restoring.
First boot the live cd and install Ubuntu.

After Ubuntu has rebooted to the HD version set up your restricted drivers for your graphics card if applicable, there is no need to reboot yet. Then replace the existing sources list with the one from your lost system. assuming that it is on an external disk (together with the /home/ directory) you would use

sudo mv /media/disk/sources.list /etc/apt/sources.list
sudo apt-get update

Then update the packages using:

cat /media/disc/package.list | xargs sudo apt-get install

If you are using some unauthorized packages you will get the following warning

“WARNING: The following packages cannot be authenticated!
libxxx libxx libx xxxplayer
skype-common skype xxxcodecs
Install these packages without verification [y/N]? E: Some packages could not be authenticated”

for some reason you cannot answer yes or no to this, it’s a bug. So simply install all of these packages using

sudo apt-get install libxxx libxx libx xxxplayer skype-common skype xxxcodecs

When that has completed run

cat /media/disc/package.list | xargs sudo apt-get install

again and this time it should complete without problems.

Now copy your /home directory to the new system using sudo grsync (preserve time, owner, permissions and group) or

sudo rsync -r -t -p -o -g -v --progress -l /media/disk/home/ /home/

That’s it! You need to reboot and your system should be exactly as it was. I have tested this three times without problems.

UPDATE 10.08.2009
The method of building and restoring a list of installed packages described above no longer works. Instead to build the list use:
sudo dpkg --get-selections > package.list
To restore the packages use:
sudo dpkg --set-selections < package.list
sudo apt-get dselect-upgrade

Microwave link engineering with Google Maps

My webtool calculates the distance and bearing between two markers. It also calculates the Rx level, Fade margin, FSL and unavailability of a link between these two markers in % and minutes/year. Furthermore if you give a required availability it will calculate the maximum link length you can achieve using given parameters and shows this graphically on the map.

You can try out my webtool at http://members.chello.at/stephen.joung/indexMW_Distance20.html Here is a short description of how to use the webtool.

You can zoom in and out with your mousewheel or by using the control in the left top corner. You move the map about by clicking with the left mousebutton and holding the button down while you drag the map.

You can enter markers three ways:

1. By clicking on the map where you would like to place a marker
2. By entering coordinates in the boxes provided above the map.
3. By entering an address in the box provided above the map. The resulting marker can then be dragged to the exact location required

The coordinates of the markers are then seen in DMS and Decimal degrees to the right of the map. Also the bearing from A-B and from B-A and the distance between the two markers can be seen. You can input Tx level, Rx Threshold, freq, polarization etc and the tool calculates the Rx level, Fade margin, FSL and unavailability of the link in % and minutes/year. You can change the parameters, ie Tx level or freq and the availability etc are automatically recalculated.

Toward the bottom of the form there is a box to input a required availability after you have done this you can press enter and the tool will calculate the max link length you can achieve with this availability and the freq, polarization, Tx level etc that you have chosen. Change any of the parameters and/or the availability required and the new max link length is automatically calculated. Click on either of the markers and the max link length is shown as a circle around the marker. Recalculate the link length with new parameters, ie horizontal polarization, new freq, Tx power etc and click on the marker again and a new circle is drawn representing the new link length. Click on any circle and info about this circle is given in a window. There is no limit to the amount of circles you can draw.

A new feature is dragable marker-B. Click on marker-B and the marker becomes dragable, drag it to a new location and release the button and all calculations are re-calculated for the new B location.

Any suggestions for improvement will be welcome.