One of the things I state in the Introductions about my books is that I use them myself as references and this week was no exception.
I perform many tasks on Linux computers for which I am responsible and a good deal of the time, that means remotely. And I don’t mean just from one room to the next. In many cases I need to do things over a distance of miles. I do a lot of things quite frequently and so I need no reminders of how to perform those tasks. But this week was different.
I had two problems on one computer for which I am responsible at a remote location and I did not have the time to drive there. Well – I didn’t want to drive there in any event. So, to fix both problems, I logged in to the problem computer from home using SSH.
And I used my own books as a reference resource for the tasks I performed.
The first problem was with VirtualBox, the free open source software I use for running virtual machines. I knew I could fix this easily because I have done it several times; it is a problem in which VirtualBox cannot compile the kernel modules for the new kernel and I need to revert to the previous kernel. So I configured grub to boot to the previous kernel by changing the line GRUB_DEFAULT=saved to GRUB_DEFAULT=1 in /etc/default/grub. Normally the “saved” option specified in that line says that every time that Linux boots, grub saves the identity of the kernel that was booted and that becomes the default kernel for the next boot.
This resolves the problem until a kernel fix can be provided. I did not need much help with this but I did check Chapter 16 of Volume 1 of my self-study series “Using and Administering Linux: Zero to SysAdmin” to verify that I remembered the right option and the right file in which to make that change. I also needed a little help with the syntax of the command required to rebuild the grub configuration file using the revised grub default file.
[root@studentvm1 grub2]# grub2-mkconfig > /boot/grub2/grub.cfg
I don’t cover this specific situation in that series so I have added this information to my technical website at http://www.linux-databook.info/?page_id=6044.
The second problem is that one of the printers available to the host was not available in the print menu when the office manager tried to print. The network printer was visible but the USB attached local printer was not. So I needed to create the print queue for that USB printer. Unfortunately, this is one of those tasks I only perform once every 3 or 4 years so I don’t really remember how to do it.
Using an SSH login session, I followed the step-by-step directions in Volume 2, Chapter 7, of my self-study series “Using and Administering Linux: Zero to SysAdmin,” Experiment 7-2, to add this print queue and test the result – successfully.
About my books
My books were written to be used as references and all of them started as memory aids for me. I would perform many tasks infrequently and it seemed a waste of time to keep doing the same research many times over. So after discovering new tools, fixes, and solutions, I started recording them so I could find them easily. Eventually I used that material as the basis to create a series of three, 4-day instructor-led courses that I taught for several years.
And then I decided to convert those courses into the books that I have written over the past several years. Because they are written in a way that can be used both for training and reference, I find them to be useful all the time. I think you will, too.