Posts Tagged ‘ubuntu’

Ubuntu 14.04: PPA key not found on keyserver

Running “apt-get update” ubuntu complains about missings ppa keys.

In my case I was trying to install Libre Office and the missing key was 83FBA1751378B444.

I couldnĀ“t find any key running:

sudo apt-key adv --keyserver --recv-keys 83FBA1751378B444

The message that I gog in the console was:
gpg: requesting key 83FBA1751378B444 from hkp server
gpgkeys: key 83FBA1751378B444 not found on keyserver
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0

The solution to me was running:

 sudo launchpad-getkeys 

and the I could finally run “apt-get update”.

Backing up the Master Boot Record in Ubuntu 11.10

The Master Boot Record (MBR) is a space of 512 bytes that holds the partition table as well as the stage 1 of the boot loader.

Making a backup of the MBR might be useful in case of damage, as the operative system wouldn’t boot.

Therefore, you can make a copy in your home directory typing:

sudo dd if=/dev/sda of=~/mbr.txt count=1 bs=512

If you type:

sudo cat /dev/sda

you can see that /dev/sda is a binary file. However you can see that the backup is a file called “mbr.txt“.

If you need to restore the MBR you can use the following command:

sudo dd if=~/mbr.txt of=/dev/sda count=1 bs=512