Category Archives: Linux

Convert multiple JPG or PNG to PDF in Linux

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I think we all have been in the situation before, you have some scanned documents in JPG or PNG format that you need to convert into a PDF file.
There are many solutions for this on the internet, including free sites that just does it for you if you upload your images, but they almost always put some kind of watermark on the pages if you don’t pay them.
There are also a bunch of Windows applications that do this, but they are often complicated or full of ads.
This guide show you a free solution on Linux, that just works, is fast, and does not add any crap to the PDF.
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Temperature measuring using Linux and Raspberry Pi

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The story

I have a small server room, with some rack servers, NAS’s, VMware ESXi’s and other fun stuff, but I had one problems.. in the summer it got really hot, and I had to open the window to let fresh air in, and the old out to lower the temperature again, but I never knew when it was too hot, so i had to drive by the server room once or twice a day to manually feel if it was too hot..
This was a problem, because sometimes I was not home, or sometimes I forgot, or just had no time to drive by to check the temp.
Having a temperature sensor in the room, from a freezer or something like that didn’t help me much, since I still had to drive by to check it manually.
So I had to make something I was able to get the room temperature from, over the internet/lan, and thats when I decided to make my network thermometer.
I looked for weeks on the internet for a good guide about this, but none of them worked. so I decided to write my own to help others with the same problem out.

This post will be about

How to make your own network thermometer, using open source software and a cheap USB temperature sensor!
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MySQL data on secondary hard disk

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Having your MySQL data on a separate partition is important, why?

Having your MySQL data on a separate partition is important because when your root partition fills up and no space is left, your system won’t be able to boot and might crash when running, you then have to boot from a recovery disk to remove files before you can boot on your normal system again.
This is critical for servers that you can’t allow to be down for an hour or two!

The solution

The solution is easy, you just move your MySQL data to a separate partition, and this problem won’t occur any longer, the only thing that happens when you run out of space, is that the MySQL can’t write any new data to the database, which is better than the entire system crashing and being unable to boot.
In this guide i will show you how to make the changes needed to get this problem resolved.
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Debian Linux server (wheezy 7.1) installation

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Debian Linux (Wheezy) server is easy to install. It takes about half an hour, or two depending on what you need it for and how “special” your installation has to be. A standard installation with only one hard drive will take about 0,5-2 hours depending on your knowledge on Linux servers.
On this page I will guide you through how to do it, with screenshots and explanations on every single one.
I have choosen Debian Linux as my favorite Linux server distribution for the following reasons:

  1. It’s light. It only got the stuff you need and nothing more, which gives you a really small footprint (Debian can run on a computer with less than 200 Megabytes of memory easily!
  2. It’s reliable
  3. Updates are stable, no crossing fingers when updating the system hoping it will not break
  4. If you ever have problems with Debian, it’s really easy to find a solutions just by Googling the problem.
  5. It’s easy to use
  6. It’s fast.

I will in this guide install Debian server without any Desktop environment (no icons, no mouse. only a keyboard and a console screen) since this saves a LOT of resources (about 100-200 megabytes of memory) and the time it takes for the server to boot/startup.
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