Daniel's spot

Missing fonts after moving /usr/share

Sun, 12 Apr 2015 01:43:15 +0000

My Ubuntu installation was accusing low space at /usr. It was a 15GB partition and nevertheless it had about 600MB free.

As I had overestimated the size of /var, I decided to reduce it (using gparted) and create another partition for /usr/share, which would give me about 6GB of free space at /usr.

Everything worked as a charm. I went about my normal day and, after a few hours of normal work, I moved to a different task. I am teaching a class and had not uploaded the slides for the students. So, I opened the presentation on Impress (Libre-Office's "Powerpoint") and most of the text was gone. I still had pictures, the titles were there, but the actual content was gone.

I pulled back some backups, nothing. Then, after a cup of coffee to clear my mind, I realized that it could be related to the changes I had done in my file system. Trying to understand better what happened, I looked at the slides again. I noticed that the missing text were using specific fonts. For example, I used courier for code snippets, and in the one single case I forgot, the code was there. Now, guess where the fonts are stored? yes: /usr/share/fonts. Everything started to make sense.

So, after poking around, I found that there is a cache of fonts and I concluded that moving /usr/shareto another partition, I messed with the cache. So, I rebuilt it and.. voi-la! It works.

If you come across a similar problem, the command to rebuild that cache is as follows:

sudo fc-cache -f -v

Ubuntu: Fixing NO_PUBKEY error from apt-get

Sun, 11 Jan 2015 19:17:31 +0000

This error is likely to appear when you added an extra repository to your sources (e.g., ppa.launchpad.net). In my case, it was due to Gnome3.

After running apt-get update, I received the following error message:

W: GPG error: http://ppa.launchpad.net trusty Release: The following signature couldn't be verified because the publix key is not available: NO_PUBKEY ≪SIGNATURE≫

Where ≪SIGNATURE≫ was the source signature and consisted of a hexadecimal representation of a large number.

The reason for that error is that I had added the repository, but not its public key. My system couldn't verify it was dealing with the right repository and not a fake one.

To fix it, we have to get the key from some source that we trust. In my case, I got it from Ubuntu. (I am using their system, so I kind of trust them anyway.)

The command to add the key is as follows:

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys ≪SIGNATURE≫
sudo apt-get update

The last command I used just to confirm everything was right. ;)

University of Calgary Alumni talk: James Gosling

Fri, 14 Mar 2014 17:57:00 +0000

Last night, I attended to a really interesting talk, given by one of the most recognizable alumni of the University of Calgary: James Gosling, a.k.a., the "Father of Java". He talked about his more recent work, and the talk even included robots in the ocean being attacked by huge sharks. He also showed to be a really approachable person, welcoming any questions he received... And it was a lot, in particular after the talk.

Microsoft: Meet the company

Wed, 26 Sep 2012 01:57:23 +0000

Quick note: Tonight (or last night), at the university, we had a little talk from Microsoft. The idea was "inviting" students to apply for a job at that company. The highlight that I have to share: at the beginning of the presentation, the Powerpoint froze. They had to call the task manager. The talk was delayed by about 10 minutes. The presenters were visibly embarrassed. Everyone was laughing. And I thought these problems in presentations were pure legend. hehehe

Trying Mageia

Fri, 27 Jul 2012 14:49:46 +0000

For the first time in a long time, I decided to go out of my "comfort zone". I would try a distro that wasn't based on Ubuntu or even Debian. I needed to change my installation anyway, from 32 to 64 bits, so I used it as an excuse for my adventure.

I decided to try Mageia, a distro which is derived from Mandriva (from the company created by the fusion between the French Mandrake and the Brazilian Conectiva), just like Fedora derived from RedHat.

Unfortunately, my experience was not really pleasing. The DVD installation didn't work. When I booted my computer, the graphical driver wouldn't work. I ended up successfully installing from the Live CD. But, with my lack of familiarity with the environment (e.g., "Where is the "apt-get" equivalent?"), I found the system quite unstable.

I even tried Enlightenment (E17)... Honestly, it was pretty but not really good. I found E17 to be too slow and with too much animation. I think that a more efficient configuration tool that allows fine-tuning might make E17 a more interesting alternative.

As Sheldon said once: "There is a reason for why it's called 'comfort zone'". So, at least for now, I am going back "home". This afternoon/night, I'd be reinstalling Linux Mint 13, (now the 64 bit variation) running LXDE. When time permits, I might do another adventure in another "foreign distro".

Solution for the ".bashrc vs ssh command" problem

Mon, 25 Jun 2012 01:18:19 +0000

Some Linux users (including myself) have been unsuccessfully trying to execute a command via SSH, for example:

ssh user@host mycommand

The problem seems to be that "mycommand" is in a directory that is not in the PATH. However, when they connect normally, they can see the directory in the PATH environment variable.

It seems that most of these users (again, including myself) update the PATH variable in the .bashrc file and, apparently, the .bashrc file is not executed when connected "non-interactively" via ssh.

After looking for a good while, many people suggested to check if the .bashrc was called by .profile or .bash_profile or something like that. Well... that did not solve my problem.

What, in fact, happened was that .bashrc was being called (or "sourced") by SSH, but the guys from the distro decided to add the following lines in it:

# If not running interactively, don't do anything

[ -z "$PS1" ] && return

Basically, the test above only allows the execution of the rest of .bashrc if it is an interactive shell, thus it does not work for my needs. Why is it there? I have no idea... anyway... I just commented the test and it worked perfectly.

Coffee for Turing

Sat, 23 Jun 2012 20:41:00 +0000

Today, the honors go to Alan Turing, the "Father of Computer Science", who would be celebrating 100 years since his birth. Among other achievements, for example as a successful cryptologist during the Second World War, he was the person who created the concept of computers and programs.

The coffee cup was a gift from ACM for my first year as member. And that coffee was in his honor.

Thank you, Mr. Turing, for creating what is now a science and the profession of many (including myself).

Now, Xoom™ing with Ice Cream Sandwich

Fri, 22 Jun 2012 14:18:04 +0000

I have recently starting using a Motorola Xoom™ with Android 4.0 (Ice Cream Sandwich).

My cellphone has Froyo (Android 2.2) installed and, comparing to that version of Android, the ICS came a long way and it's a lot better. First thing I noticed was that we can now organize the home screen putting Icons into "folders", just by moving an icon over another one. While I used all the five home screens in my cellphone and feel I needed more, with this feature, I don't use more than 2 home screens in the Xoom.

What I didn't like much was the camera. I have tried to take pictures of my daughter and I barely can get one that is not blurred. (Granted, my daughter simply can't be still for a picture... too much energy!) On a good side, I really like the landscape option for the camera. It worked nicely... Now I just need to get an opportunity to find a nice landscape to photograph.

In terms of performance, I don't know if it's because of the limited number of applications I am using, but I really find the tablet to be quite fast and battery has lasted a bit more than one day (with moderate use, which I find it to be acceptable.

Also, I liked the fact it has 32GB of internal storage (which is a lot compared to other products) and still accepts micro-SD card.

My favorite apps for it, so far, are:
- ConnectBot: a SSH client for Android
- Hacker's Keyboard: A substitute for the original keyboard that gives you a PC keyboard on screen (with numbers over the first row of letters, for example).
- Apex Launcher: "Launcher" is the android equivalent to Windows Managers in Linux. This one is quite light and provides some nice customization options, including number of home screens and animations.

Coffee helps preventing Alzheimer�s

Sat, 16 Jun 2012 14:13:00 +0000

I had already heard that Coffee would be good for memory, but things seem to be even better.

A recent study from University of South Florida and University of Miami with older adults (over 65) who drank coffee regularly during their lives (about 3 cups a day) had less chances of developing Alzheimer's.

Coffee on Saturdays

Sat, 19 May 2012 21:39:00 +0000

Starting today, this blog will have, as much as possible, "Coffee on Saturdays" (temporary name). This idea was inspired by another blog and for recent news.

The blog is by Bruce Schneier. He has what he called "Squid Fridays", with random posts about... squid. I mean the animal, not the software. I hope Bruce doesn't mind my adaptation of his idea.

My other inspiration was recent news about coffee. As many of my friends know, I am rather addicted to coffee, and I mean the drink, no references to the programming language. While some people consider coffee to be bad for one's health, this week I learned that a study from US National Institutes of Health, and to be published on the New England Journal of Medicine, suggests the people who drink 2 to 3 cups of coffee a day has less chances of dying from a number of causes. The list of causes includes heart and pulmonary diseases, diabetes and even accidents.

So, from now on, I'll try to keep my Saturday's posts somewhat related to coffee.