Tar on Michael’s Domain

BackupPC and Macs

Wed, 13 Apr 2016 00:00:00 +0000

I myself have been using the backup software BackupPC for almost a decade, and I started to backup our lab computers to a central backup server about two years ago. BackupPC supports deduplication and therefore much data can be stored on a couple of 2 TB drives.BackupPC supports many protocols (smb, ftp, tar/rsync via ssh), but we mostly use rsync via ssh. The data is not encrypted before the backup. Strangely not even the upcoming version 4 will support pre-egression encryption. However, we store the backup on an encrypted volume. That way it is at least protected if the backup server is stolen. And during transit, the data is protected by ssh. However, the system is not TNO (“trust no-one”), since I (as the backupc administrator) can access the files. When using Linux, one feasible method would be to encrypt the user’s home directory using eCryptFS (which is an inbuilt option when creating users on Ubuntu ) and then backup the /home/.ecryptfs directory instead of the users home directory. However, recovery would be much more of a problem. You would be able to browse the diectory structure and files of the backup, but the filenames would be meaningless since they are also encrypted in the process.There is one peculiarity in backing up Mac OSX machines: BackupPC normally connects as root via ssh into the client computer and executes the rsync backup command. In order to make this possible on university-managed Mac OSX computers, we had to create a dedicated user (“backuppc”) on the client machines and allow for this user the execution of rsync with root privileges, which is done by adding this line in the /etc/sudoers file:backuppc ALL=NOPASSWD: /usr/bin/rsync. Then we have to change the ssh/rsync command for the Mac client on the backuppc server changing “root” into “backuppc”.

Disk dumps (dd) and copying over the network (netcat)

Tue, 16 Feb 2010 00:00:00 +0000

On the receiving machine (disk sda MUST be unmounted, e.g. by booting from a live CD or USB stick):netcat -l -p 4778 | dd of=/dev/sdaOn the sending machine (disk sdb MUST be unmounted, e.g. by booting from a live CD or USB stick):dd if=/dev/sdb | netcat 192.168.0.4 4778(-l listen; -p port)To copy a directory over the network, enter the directory and execute on the sending machine:tar -cz . | nc -q 10 -l -p 45454On the receiving machine, create the directory, enter it and execute:nc -w 10 192.168.0.11 45454 | tar -xzBTW: If you want to see the progress of a disk dump (how much was already copied in what time at what average speed), you can use (in newer versions of dd) the status option. I guess this might not work for network copying, but I have not tried… dd if=/dev/sdb of=/target status=progress

tar copying via ssh

Fri, 26 Sep 2008 00:00:00 +0000

tar czv sourcepath | ssh -l username 192.168.0.5 tar xz -C targetpath

Sequence trace files in tar archives (Staden)

Thu, 05 Apr 2007 00:00:00 +0000

I want to store all sequence traces of a sequencing project (using Staden) in one file. You can do that if you simply tar all the *.ztr files: tar -cvf ./test.tar *.ztr Then you have to specify in gap4 Options -> Configure menus -> Expert And then you need to specify Options -> Trace file location -> TAR=./test.tar

How to back up hidden files

Wed, 04 Apr 2007 00:00:00 +0000

tar cvf backupfile.tar .[a-zA-Z0-9]*Any better ideas? This command requires that the dot is followed by an alphanumerical character. Which is usually the case for the hidden files in the user’s home folder.

Backup your home directory using tar

Thu, 16 Nov 2006 00:00:00 +0000

As root go to /home directory and execute the command:tar -czvf pathto/archive.tar.gz username