Rename an Amazon Lightsail instance

Amazon Lightsail is a perfect solution for a newbies to cloud computing like me. It offers a very simplified interface and overall approach into creation and management of fully featured VPSes (Virtual Private Servers) without the overhead and hassle of using more complex and more professional solutions like Amazon EC2.

The most important part of its greatness, next to simplicity, is pricing. The smallest possible option (just a virtual server with:

  • 512 MB memory and 1 core processor
  • 20 GB SSD disk and 1 TB of outbound traffic per month

which is far enough to host a simple-to-middle WordPress site will cost you 3.5 USD per month only. One static IP (with the possibility of using your own domain thus) is added free of charge.

You will be billed more only if your site has enough interest to go beyond that 1 TB outgoing traffic or if you decide that you need more computing power. Other than that — just a plain three and a half buck per month.

However, there’s a little glitch when you create your instance with an incorrect or misleading name, because the process of renaming Amazon Lightsail instance includes a few steps and some downtime on your website.

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Fix incorrect mp3 duration with mp3val

I’ve found a few files for which:

  • Video LAN for Windows was playing them without any problems (after a 1 second glitch),
  • Winamp for Windows was playing them also without problems, but showing 00:00 as each file’s duration
  • mobile player for Android failed to play them showing Cannot play content error.

A quick look-around the Internet showed that a tiny mp3val program can validate any .mp3 file and fix most errors, it finds.

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Batch remove silence from many MP3 files

I’ve downloaded over fifty one hour long recordings of my church-related celebrations. As with most of such recordings, every file contains about 5-6 minutes of:

  • silence or
  • non-related sounds

in the beginning during priest’s processing, people gathering etc. Plus it concludes some silence during various moments of celebrations. I wanted to get rid of it.

I found this eleven years old question at Super User. It’s not only very old, but also off-topic (no software recommendation-like questions allowed at SU) so I decided to put my own update here.

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Print two A5 pages on singe A4 paper sheet

Suppose you have a Microsoft Word document that is formatted to be printed on A5 pages. For any reason (you don’t have A5 page, you want to save paper etc.) you want to print it so that two A5 pages will appear next to each other on single A4 page.

On contrary to common beliefs this is not as easy as selecting 2 Pages Per Sheet because, without additional settings, your printer will be still asking you to feed it with A5 paper.

It’s not that easy, but the solution is still surprisingly simple.

This article is specific to (ISO 216 standard) paper size standard and for printing two A5 pages on one A4 sheet. But the very same steps should theoretically work in every scenario where you want to print two half-sized pages on single page format that is twice as big. Thus, printing (plotting?) two B3 pages on one huge B2 poster should work. Or printing two Letter-sized pages (216 × 279 mm) on one Ledger page (432 × 279 mm).

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Reverse dates in filenames using Total Commander’s multi-rename tool

Multi-rename tool in Total Commander is fantastic (when you know how to use it) and it saved my ass (before manually renaming many files) in many scenarios, including some very specific or even weird ones.

This scenario is one of such.

I had dates written directly as a part of filename, i.e.: Document name (DD-MM-YYYY).jpg, but (as shown) starting with day and ending with year. I had to reverse them, but only dates, keeping the rest of file untouched — i.e. Document name (YYYY-MM-DD).jpg.

At first, I thought that this time I will be forced to do this manually. But, I recalled multi-rename tool’s documentation and its small part about backward characters counting (i.e. from end of filename).

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A very quick introduction to QEMU

If you’re developing your own applications for Raspberry Pi:

There’s a never-ending question on testing your results.

Copying:

  • New version of your app into Linux on your RPi and running it or
  • New disk image to microSD and booting entire device

Doesn’t seems to be a huge problem.

But, when you have to do this dozens of times each day than an emulator-like questions appears.

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Get some base Linux info in QNAP TS-210 using console

QNAPs runs on (sometimes heavily modified) Debian distributions. But, what about kernel version etc.?

There several ways of getting this information from console. Out of them following works on TS-210:

  • uname -a
  • cat /etc/issue
  • cat /proc/version

If you ever need more information on this then… LMGIFY.

In this article I’ll show you the very basic commands that can be used on QNAP TS-210 (modified Debian Linux) to obtain system release, version, hardware info etc.

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Border-less full-screen console app in Ultibo

I made my first project in Ultibo and compiled some example one. Everything was just fine (actually — perfect), if not for that green border with Ultibo name and release version.

Don’t get me wrong. I already love UItibo and will spread the word. But, for security reasons, I’d like to get rid of any info that clearly communicates what was used to build particular piece of software.

Fortunately, with a small research (here and here), it turned out that the solution is very easy.

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Error code 6009 when deleting folder from OneDrive

If you’re getting “Error Code 6009” during attempting to delete any folder from OneDrive:

Then look carefully for all open browser windows and tabs. Because this error means that you are trying to delete a folder which contains any file that is already opened in some window or tab.

If you cannot find any tab or windows of such kind then restart browser and try to delete folder again (alternatively, restart the whole computer). As there maybe some background task, not visible to you, that is holding a file lock and preventing you from deleting a parent folder.

3.5 inch GPIO display and RPi

There are a lot of displays for Raspberry Pi. We can list them by image technology:

And by connection method:

There are a lot of arguments and parameters to consider when picking one that is best for you:

  • DSI is the most expensive, but leaves both HDMI and GPIO port free
  • HDMI is cheaper, but occupies one USB port (powering) and of course HDMI port
  • GPIO is the cheapest solution, but occupies GPIO port which is not acceptable in most scenarios

I have decided to buy the last one because it was purely for testing purposes.

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Doing IT in Switzerland

I have a chat with a HR guy from Switzerland. He gave me some wages for the IT (May 2021; post-COVID!):

Most likely gross, but still… Swiss IT is doing good. Really, good…

Get started with Raspberry Pi

In this quite old article I have provided just a typical non-sense introductory blah, blah about playing with Raspberry Pi. People who hasn’t done anything yet to their RPi box where sent there to the original “Get started with Raspberry Pi” article at the RPi’s homepage.

Now, it is time to write my very own “getting started” article. A short list-command memo of what should be considered after you unpack, power up and access via SSH your next RPi box.

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Login as root user to Raspberry Pi

As in this article, you cannot login as a root user in Raspberry Pi (neither locally nor via SSH), because you don’t know the default’s root password. In this article, I’ll show you how to change it to be able to login to it, but only locally (still no SSH access), which is good.

Again, as in here, you should never, ever access or use root account. Instead you should use pi user (after changing its default password) and elevate it to superuser with sudo su or by casting sudo in front of each console command.

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Various wako problems with Alt+Tab and Microsoft products

Ever since Windows exists there was a very handy Alt+Tab combination to quickly switch between open applications. Nowadays, when people are using many screens for single computer it might be less often used, but still is very familiar and handy.

Not for so long time, but still for quite long, Microsoft is doing everything to make that simple, obvious and easy to understand combination work as wrong as possible in their products, so from time to time you may run into a really weird behaviour. For example:

Fortunately these inconsistencies and workflow breakers exists only in certain Microsoft products and are easy to fix.

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MEGA — file sharing and cloud storage far above average

The IT world grows, big data becomes your everyday’s pal. Whether you are a developer or project manager, you need to store more and more data each and every day. Getting a good quality and reliable solution becomes a bit challenge. To help you with that I wanted to tell you a bit about MEGA service.

I found it by a complete coincidence (I am not getting paid for this post!) — a friend has shared a file with me. I dug into details and found it interesting. In my opinion MEGA is far better than most file sharing services and can challenge even well known cloud storage options like Google Drive, Dropbox or OneDrive.

So, what makes MEGA that unique? In short: command-line tool, NAS support, mobile apps, browser’s extensions and many more.

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Force Microsoft Edge to safe images with .jpg instead of .jfif extension

There are million of guides in the Internet on how to correct this stupid default behavior that happens in Microsoft Edge nearly every time and in Google Chrome from time to time. But all these solutions requires you to read through long block of text or watch 2-3 minutes long video while solution is actually ultra-fast.

  1. Start > type regedit > hit Enter
  2. Paste Computer\HKEY_CLASSES_ROOT\MIME\Database\Content Type\image/jpeg to address bar > hit Enter
  3. Double click on Extension > paste .jpg > hit Enter

And… you’re done! Restart Edge to see the effects. No more .jpg files saved with stupid .jfif extension.

keepachangelog.com of your stuff?

I am not intend to tell you that you should keep a change log of any piece of software that you ever develop. This is as obvious as the fact that sun shines and fire burns. If you don’t understand this or disagree then you’re certainly at the wrong address.

However, with this article I am going to tell you about a specific way of keeping history of changes to your software. The one that keepachangelog.com suggests. The one that I immediately fell in love with.

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Temp Mail and Temp Number for QA purposes, but not only…

The Temp Mail and Temp Number services were originally created (according to their owners) to lift of your problem of being bloated with stupid newsletters and SPAM emails and text messages, when you use your actual mailbox address or phone number in order to register to some service.

With these services you can totally forget about such pains because you’re getting a fully working email address or SMS receive-enabled phone number that will self-destruct after twenty minutes or so.

If you are a developer you may already catch an idea that you can use this for a QA purposes.

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All Raspberry Pi default logins and passwords

I don’t like unnecessary blah, blah and I don’t like blogs bloated with ads, so I decided to steal this source and transform it into a simple list of default logins and passwords on various Raspberry Pi bases and clones.

All the glory (copyright and authorship) goes to tutorials-raspberrypi.com.

You read more about users at base Raspberry Pi (no clone) here.

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Put significance on tens and ones or round to a negative precision [updated!]

I had a situation in Excel where tens and ones are the only significant parts of a any number. For some Polish language-specific issues I have come with the situation that no matter how big number is, I need to know the value of its last two digits or last digit.

For example:

21 --> 21 and 1
56 --> 56 and 6
160 --> 60 and 0
1122 --> 22 and 2
679014 --> 14 and 4
1053405 --> 5 and 5

Learning the fact that ROUND(), ROUNDUP() and ROUNDDOWN() functions in Excel can be used with a negative precision parameter helped me solved this issue.

I am not too good in Excel, so maybe (update!) there are prettier solutions. This one works, however…

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Introduction to curl

This is just a barely memo about very, very basics of curl. Since curl fetches URLs and data from some endpoints, it can be used for a variety of reasons. I am using to for a very basic (and quick!) API calls tests.

If you’re on Linux, Unix or any of its clones or if you’re on Mac then you most likely have curl. If you’re on Windows, but you’re using Git for Windows (or some similar tool) then you have curl.

So, let’s jump into that basics. Be warned — you will not find here anything that you wouldn’t already knew.

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Developing applications for Raspberry Pi or Linux

Depending on: project’s scope, business expectations, your knowledge and Raspberry Pi’s role you can develop software for RPi in mainly three ways:

  1. Turn Raspberry Pi into API-like webserver with node.js and do all the programming in clients.
  2. Develop a HTML/CSS/JS application
  3. Develop an native Raspberry Pi app

All of the above require you to:

  • Develop a regular Linux app
  • Optimised to use hardware and computing power of Raspberry Pi
  • Run it in Raspbian OS or any other Linux distribution of your choice

And, if you really want to get your hands dirty and truly have no limits then you must forget about Linux and start thinking about Ultibo (there’s a separate article for that).

Developing in Ultibo (or similar complete embedded development environment) requires a lot of expertise, development knowledge and practice. And simply isn’t an option for all. Especially, if you only need to build a quick-and-easy app for RapberryPi. For these purposes this article lists details about RPi development.

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The smallest Linux for Raspberry Pi?

There are dozens of articles similar to this, so I treat it just as another quick memo for myself:

  1. You can create custom Linux-based system yourself with tools like:
  2. A ready out-of-the box solution is Core Linux / pi Core:
    • some info: here, here and here
    • very modular, add whatever you need
    • smallest version is claimed to have only 10 MB with GUI!
  3. Smallest Rasbian OS is 0.5+ GB in size so is out of option.

And if anything above is not for you then maybe a… non-Linux solution for your RPi?