Posts Tagged ‘ubuntu’
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
I couldn´t find any key running:
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 83FBA1751378B444
The message that I gog in the console was:
gpg: requesting key 83FBA1751378B444 from hkp server keyserver.ubuntu.com
gpgkeys: key 83FBA1751378B444 not found on keyserver
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0
The solution to me was running:
and the I could finally run “apt-get update”.
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