Have you ever gotten a pdf with one of those annoying passwords? A while back I bought an e-book and it came with a password. Its really annoying especially if I want to read it on a mobile device. Anyway if you are annoyed as much as I am fear no more. Install qpdf aptitude install qpdf Decrypt your pdf qpdf --password=password --decrypt input.pdf output.pdf
Over the last couple days I’ve briefly talked about revisioning configs and making your home directory portable. It seems to have stirred up a bit of discussion over at Matt Simmons Standalone Sysadmin, and Hugh Browns mentioned he uses mercurial for this task.. As I noted in the post about managing /etc with version control I do revision my home directory, or at least pieces of it.
Seems like we are on a bit of a roll with regard to the topic of versioning lately. Yesterday Legooolas commented about using version control for your home directory. I do and I’ll cover that in a different post but I use it for a different task. Now on to todays topic. Do you keep track of configuration changes? You should. Maybe your using an advanced configuration management system like puppet.
Every time I have a new shell account I end up customizing it. Making alterations to my vimrc, screenrc or whatever. It can be a huge pain when you have lots of slightly varying configs on different machines. I wrote this little script to grab my files and create a self extracting shell script so I can easily setup my environment on multiple machines.The usage is pretty straightforward. Define your remote path, and the filename along with your user that has scp access. Then define the files you want to include. To create the archive just run the moveout script. Once the self extracting script is uploaded you can just download it and execute it.
Waddya know I’m not the only geek with an affinity for the console. This could be interesting. Repository of useful one liners.
Yesterday I wrote about CPU Performance Analysis in Linux. I explained how to tell if you are experiencing a CPU bottleneck. This is just a quick followup to show the effect of adding more cpu power.
A while back I wrote a post Analyzing Linux System Performance and Finding Bottlenecks. I did’t really give a good explanation of determining if you are CPU bound or not so I am writing this post to clear that up.
Have you ever experienced hard lockups and seen no trace of the cause in your log files? Those situations can be even more of a pain if you do not have physical access to the machine since you will not be able to look for kernel oops on the console. You could buy a serial console or an ip kvm but if you don’t have the need for remote control, but would really like to be able to debug without being physically present you need to check out netconsole. Netconsole sends printk messages over UDP.
Ever run into a situation where passing the option single to the kernel wasn’t enough to get your root password reset? This is not Debian specific but some distros (including Debian) require that you still enter the root password when booting to single user mode. This is just a quick run through of how to reset your root password without a live cd. Reboot your system and at the grub prompt hit e to enter edit mode, then select the kernel line and hit e again. Now append single init=/bin/bash to the line. Hit enter to temporarily save it and hit b to boot. Shortly you will be dropped at a root prompt, now you just need to remount your root file system rw so you can update the passwd.
I was restoring some files from backup today and ran into a few files that had leading slashes. Whenever I see those kind of things I rename the files since they are a pain to work with in the shell. If you find yourself at a shell and need to work with files that have a leading dash just use the relative path and include the dashed filename in quotes.