Today I got to work on a document including a few expressions (multiplications and a sum.) That was in a table that looked something like this:

In my case, I made a copy/paste of such a table and I went ahead and deleted Thing #2 and Other #3 because I did ...

One of our computers was setup to delete rows from a database. Anything older than 90 days should be deleted. Only the script to run that DELETE had the incorrect IP address and we weren't watching the database closely so it grew to over 107 million rows and on a small VPS that filled up the hard drive.

At that point, trying to run the DELETE command would generate this error:

ERROR 3019 (HY000) at line 1: Undo Log error: No more space left over in system tablespace for allocating UNDO log pages. Please add new data file to the tablespace or check if filesystem is full or enable ...

Unix in Colors

Whenever I run a command without piping it through less, I generally get colors.

This is true in this century that computer started to use more and more colors in the console. It's practical for all sorts of reasons.

However, you lose those nice colors when you want to use "less" to paginate the results. There are two reasons for that:

Terminal vs. Pipe

The fact is that many tools will check their stdout and determine whether it's a terminal or not. If not, it can generally be assumed that it's a file, a pipe, a variable, etc. and therefore a ...

Today I learned that by default Ubuntu doesn't install an MTA.

I've been installing Postfix on my computers and never noticed that because it's like part of the things I install even before I start doing anything on my computer.

However, a default basic Ubuntu install comes bare and does not offer a sendmail tool.

Looking at a certain number of computers, I noticed that the /var/mail folder was empty. That in itself wasn't really anything to worry about, but I was still wondering, how come?! I run CRON on those 13 computers and it never fails??? Oh yeah because on my ...

(Picture above represents the logo of Ubuntu, a Linux distribution.)

The following is a list of the Ubuntu Releases with their versions and their name.

I find it really annoying when someone says "I have such" and he/she has no clue what version (i.e. 7.10) it is. Then I have to look it up because I don't memorize the numbers to the names, but I know what the numbers entitles.

So... I need a table and I had one on Wikipedia, but that was wiped out. So now, I'll keep my own here and I'll try to keep it up to date. I start with the version Mar 16, 2009 from the Ubuntu ...

Create ISO File to Burn

When creating a CD you use mkisofs (make ISO file system--ISO stands for International Standard Organization, a non-profit organization used to write standard procedures used in business and other places to better organize interoperability between many companies in the world.)

mkisofs -o my-cd.iso directory

The "directory" are all the files you want to write to the ISO file.

Verify Disk Before Burning

Then you should verify that it looks as you expected. This is done by mounting the ISO file:

sudo mount -o loop my-cd.iso /mnt/cd

Assuming ...

Ordeal

Today I made a mistake and create the file /etc/sudoers.d/timeout which was definitely not compatible with sudo. The file was JSON when sudo only accepts very basic var=value lines.

Result?

I could not use sudo anymore on that VM. I had to find a way to fix the file system without having to rebuild the entire disk because that would have taken way too long.

How to Mount a VDI File

Since your VDI (VirtualBox Disk Image) files are literally disk files, they should be mountable, right? Yes! They are. Actually, that's certainly exactly what the VirtualBox code does, but ...

Introduction

When I create a new DigitalOcean droplet I have to run a few commands that I don't otherwise use very much at all so I was thinking that adding them here would make it easier to remember.

Creating a New Key with ssh-keygen

I use the same key for each group of computers I manage there. Each time I create a new group, I create a new key with the ssh-keygen command as so:

% ssh-keygen -t rsa
...
Enter file in which to save the key (/home/alexis/.ssh/id_rsa): ...
...

WARNING: as we can see ssh-keygen asks you to write the resulting keys using the default ...

Situation

I had some problems (and may still have some problems) with a computer which at times drops its transfer speed to 100Mb instead of running at full speed (1Gb).

I think that one possible problem is that the card detects a "weak" cable, probably because it's a very long one.

Today I was surprised that it ran at full speed, though. I really thought that the network card was dead for good, especially because I tested with a MS-Windows laptop which would get the 1Gb transfer rate as expected.

Linux

Discovering Connections

Under Linux, you first need to ...

In an Excel Spreadsheet (Microsoft)

I have been wondering how to lock a few rows and/or columns at the top-left in Excel. I have seen that being done many times, but did not know how to do it myself...

In the Windows menu (Before Office 2007) and in the View menu (Since Office 2007) you will find an option named Freeze Panes. You have three selections:

1. Freeze the selected top rows
2. Freeze the selected left columns
3. Freeze the selected top rows and left columns

If you just need one row and/or column, place your cursor in the A1 cell (the very first top-left cell).

...