A backup script

13 Nov

Edit (nov. 17): I just realized I completely forgot to link to the file. Sorry. Here it is.

I got a external hard drive for Christmas last year to store some of the less important/larger things that I didn’t need or want on my internal 60GB hard drive. At some point I decided that it was impractical to continue backing up to DVDs and that I would have to use my external drive to to hold the backups unless I wanted to buy a tap drive (which I didn’t). So I manually copied my user file onto the drive every once in a while. I got really tired of how long that took so I started using rsync to manually backup the files. At the time I didn’t know anything about bash scripting but I though a shell script would be very useful so I didn’t have to type out the whole command (I’m lazy). I found the sites that I mentioned in the last site of the week and looked up what I needed to know to make a very simple shell script. I used that very simple script for several months until my brother started pushing me to add features and make something that other people might want to use. I’m glade he did this because as a result I learned a lot more about bash scripting and I have a much more functional and robust script. This script, after a few months of tweaking, is now at a point where I’m not embarrassed to let other people use it; It does everything that I want it to do (save 1 thing) and more importantly it is in complete working order.

So what does this script do?

  1. In place backups using rsync (as in it just keeps a folder up to date)
  2. Incremental backups
  3. backup of applications (I’m a mac user so I don’t think this would be a useful feature on Linux or BSD)
  4. restore

I bet your asking yourself “what is that feature that he wants but didn’t implement? and why didn’t he just go ahead and add it?” The feature is encryption (using gpg) and I didn’t add it because I couldn’t figure out how to get it to work in the way I want. For now if you want to encrypt it you will just have to do it by hand like a real man/woman.

If you have a large amount of data that needs to be back up it will take you a while so it is best to schedule the backup at night (if possible) or at any other time that the computer will be on but not in use. My user file is currently 22GB and I use an external USB Maxtor drive. With my setup it took me almost 9 hours for an incremental backup with a resulting file of 21.8GBs and 7 minuets for a normal+application backup. 21.8GBs is a a large file and only 1% smaller than the normal size of my user folder (assuming that it hasn’t changed in size significantly since I backed up last) so I may end up cutting out the compression in the future to save time. This talk of size brings me to another topic. My external drive is only 160GBs so I can’t fit very many backups on it which is the only reason there is an in-place backup in this script. In the future I may get a larger drive and remove the in-place backup.

I have only tested this on my computer (ibook G4) so I can’t guarantee that it will work on Linux. I am positive that it will work just fine on all Mac os X systems execpt that it uses bzip by default for incremental backups and mac os doesn’t come with bzip pre-installed, so I added an option (-g) to use gzip (which is installed by default.

There are a lot of different backup scripts and programs out there that may be far better than this one so feel free to stick with those if you want to. I don’t care how you backup your stuff as long as you do it. I’m sure you all know why it is important to back stuff up so I don’t think I need to get into that, however, I will say that just having a backup script/program is useless if you don’t use it. So Automate it!

Any bug reports/feature suggestions/patches can be left in the comments (in plain text please) or emailed to me (no I’m not going to give you my email address you have to find it yourself (I don’t need more spam.(by that I mean I don’t get spam and I don’t want to start(I’m not sure this is grammatically correct))))

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Posted by on November 13, 2007 in backup, bash


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