Creating individual image files from presentation slides

How do you create full-screen images from each of the slides of a Google Docs presentation without too much manual work? For the previous blog post on my Munin keynote, I wanted to include some pictures from my 90-slide presentation. There is probably a point and click solution to this problem, but it is even more fun to use some command line tools to help out. These commands have been tested on Ubuntu 19.10, but should probably work on many other systems as well, as long as you have installed pdfseparate and convert.

After exporting a PDF from the Google Presentation, I made a separate PDF file of each slide using this command:

pdfseparate input.pdf output%d.pdf

This creates a bunch of PDF files with a running number. Then I ran this little for loop:

for i in *.pdf; do name=`echo $i | cut -d'.' -f1`; convert -density 200 "$i" "$name.png"; done

And voila, then I had nice PNG files of all my slides. I found that the trick is to use the “-density 200” setting (choose the density that suit your needs), since the default resolution and quality is too low.

Installing Ubuntu on a HP Pavilion laptop

So I decided to install Ubuntu on my daughter’s new laptop, more specifically a HP Pavilion. The choice of this particular laptop was because it looked nice, and had good specs for the money. It was first after the purchase I read all the complaints people have about the weird UEFI implementation on HP laptops. So I started the install process with some worries.

Reading on various forums, people seemed to have been doing all sorts of strange things to be able to install Ubuntu on HP laptops, including modifying the UEFI setup, changing the BIOS, and so on. I recall that on my Lenovo laptop I had to work quite a bit to turn off all the fancy auto-Windows-stuff.

I am not sure if HP has changed something recently or not, but the final procedure was super-easy: I just hit the F9 button on startup and got a normal “old-school” boot selector. Here I chose the USB drive, and the Ubuntu installer fired up.

I have installed Linux (primarily various Ubuntu versions) on a number of laptops over the years, and it is very seldom that I get into problems with drivers. Also this time things went smoothly, everything worked perfectly right after the install. I think it is important to continue repeating this message, because I still hear people saying that it is tricky to get Ubuntu to play with different hardware. True, there used to be driver issues some years ago, but personally I haven’t experienced that in five years or so.

Which Linux version to choose for a 9-year old?

My 9-year old daughter is getting her first laptop. But which OS should she get started with?

I have been using various versions of Ubuntu as my main OS for around 5 years now, currently using Ubuntu Studio on my main laptop. This distro is based on XFCE, a very lightweight yet versatile OS. The reason for choosing Ubuntu Studio over the regular XUbuntu was to get a bunch of music apps by default. I haven’t been able to explore these as much as I wanted to, unfortunately, primarily due to everything happening at our new centre (RITMO) and master’s programme (MCT).

Even though I like Ubuntu Studio myself, it is not a distro I would install on my daughter’s machine. Buying a new computer with Windows 10 pre-installed, one could argue that it would be best to leave her with that. This may also help her to be more familiar with the computers they are using at school, which run Windows 7 at the moment. But the question in the store about whether I wanted to buy some antivirus-software with the new laptop, was enough to ensure me that a Linux distro would be a better choice.

I have heard that some people like distros such as Edubuntu for kids, but it does not seem to be maintained? After thinking about it for a little while, I have concluded that it is probably useful for a kid to learn to use a normal OS. If you compare how things were a decade or two ago, most modern-day OSes are comparably easy to use anyways.

Finally I decided to make it simple, and installed the regular Ubuntu distro based on GNOME. It looks “modern”, has large icons, and is fairly easy to navigate due to the streamlining of menus, and so on.

Rotate lots of image on Ubuntu

I often find myself with a bunch of images that are not properly rotated. Many cameras write the rotation information to the EXIF header of the image file, but the file itself is not actually rotated. Some photo editors do this automagically when you import the files, but I prefer to copy files manually to my drive.

I therefore have a little one-liner that can rotate all the files in a folder:

find . *.jpg -exec jhead -autorot {} \;

It works recursively, and is very quick!