iniy.org

My 3D printing journey

Fri, 21 Jun 2024 20:15:50 +0000

I am 3D printing for a while now and want to share my experiences so others can benefit from it and maybe also get motivated to start with this fascinating hobby.

I will cover my beginning with a 3D pen, my experience with Ender3 and lately the Prusa MK4.

Kubernetes Requests and Limits explained

Fri, 02 Feb 2024 19:39:46 +0000

During my work as IT freelancer I frequently I encounter common misunderstandings about the kubernetes requests and limits which lead to unstable systems and wasted resources.

So this blogpost explains what the meaning of the different values is and how to set them properly.

Find all ubuntu packages not from standard repositories

Fri, 24 Feb 2023 09:55:46 +0000

When upgrading from one ubuntu version to the next one, I like to use the opportunity to do some spring cleaning.

To find from which repositories a package was installed we can use:

dpkg -l | grep "ii" | awk '{print $2}' | xargs -n 1 -IX sh -c "apt policy X 2>/dev/null | tr '\n' ' '" | tee all_packages.txt

Then we can inspect the all_packages.txt file and filter for packages which are not from the ubuntu repositories.

Golang for Java-Coders

Sat, 02 Dec 2017 12:21:07 +0000

The mocking gopher: a fitting mascot for golang

I want to share my experiences when I started programming in Golang from my perspective as a Java Coder.

What is this and why???

So first I wanted to know what is Golang. Rumors from my colleagues put it into one class with C and C++ (which it is not), this is not true at all. Golang is not a low-level language, it is far closer to Java than to C (from an abstraction perspective). These rumors probably come from the fact that it has a small amount of keywords and control structures reminding a bit of C.

Migrating from Vaadin 7 to Vaadin 8

Fri, 24 Feb 2017 04:26:49 +0000

Hohoho, Vaadin 8 is out!

Last night I couldn’t sleep and having read the release announcement of Vaadin 8 on the Vaadin Blog ( https://vaadin.com/blog/-/blogs/vaadin-framework-8-is-out ) I was curious to give the new version a try.

WTF: physical scrum boards

Thu, 12 May 2016 16:59:36 +0000

On every scrum project I have the same discussions with the scrum master. Why on earth would we want to use a physical scrum board? I then hear some cultish praises of awesomeness in favour of the physical scrum board and total neglectance of any arguments against it. That goes so far that the scrum masters seems to be experts on office supply brands and field tested ripping-off techniques for post-its. People start writing information (about two words from a 200 word description) from a ticketsystem on a post-it and making photos of the physical scrumboard to re-digitize it.

Flashing Cyanogenmod 11 on the Samsung Galaxy S3 Neo+ GT-I9301I

Sun, 31 Jan 2016 01:59:35 +0000

He tried to flash his S3 Neo!

Repeatedly I went to a lot of pain flashing my S3 Neo because I did not write down how I did it the last time, but not again!

This tutorial assumes you know what you are doing, you can brick your device, blablabla, read the disclaimer on the firmware sites.

Using Docker in Production

Sat, 07 Nov 2015 21:07:50 +0000

Linux containers are around for quite some time and docker has built a nice toolsuite around the kernel-features for process-isolation (namespaces, cgroups, etc.). The isolation technology is part of the kernel for about 8 years now, so it probably can be considered mature. Big distributions used in commerical environments like Redhat and SUSE linux officially support docker (their packaged versions of it) and provide own base images (only downloadable in the subscriber portals). Also there are companies running huge docker clouds in their daily production business.

Lenovo E540 Standby Problem on Ubuntu 14.04

Fri, 27 Feb 2015 00:03:58 +0000

UPDATE: Lenovo fixed the Bios, after a bios update standby + USB 3.0 enabled work. I used the geteltorito.pl-method descriped in the thinkwiki: http://www.thinkwiki.org/wiki/BIOS_Upgrade

I was furious about a very annoying standby problem my new Lenovo Laptop had. When closing the lid or choosing standby by the menu I did not hear the disks and fans spin down. Instead it kept running. When I then opened the lid, the backlight or something else shined, but the display stayed all black. The only solution was to keep the powerbutton pressed for a hard shutdown. The only solution for now seems to be to:

Converting videos with ffmpeg to webm format under Ubuntu 14.04.

Thu, 15 Jan 2015 08:00:55 +0000

I just love ffmpeg, because it is so easy to use and scriptable.

Install FFMPEG on Ubuntu 14.04

sudo apt-add-repository ppa:jon-severinsson/ffmpeg
sudo apt-get update
sudo apt-get install ffmpeg

Convert a video to webm

ffmpeg -i video.avi -c:v libvpx -crf 10 -b:v 1M -c:a libvorbis -q:a 6 -threads 4 video.webm

Guide to limits.conf / ulimit /open file descriptors under linux

Fri, 04 Jul 2014 18:43:00 +0000

Why does linux have an open-file-limit?

The open-file-limit exists to prevent users/process to use up all resources on a machine. Every file-descriptor uses a certain amount of RAM and a malicious or malfunctioning program could bring down the whole server.

Unit-Tests with Fortran using pFUnit (supports MPI)

Sun, 16 Mar 2014 14:16:52 +0000

Real world example

A friend of mine is meteorologist and wrote a radiative transfer model in fortran and finally we integrated pfUnit into cmake (autoinstall!) and he wrote some first tests.

Have a look here for the code:

Secure wiping your harddisk

Sat, 15 Mar 2014 19:36:30 +0000

This is a little FAQ about securely wiping your harddisk.

Why is deleting the files not enough ( e.g. rm -rf *)

Because this removes only the meta-data to find the data, but the data itself is still there. It could be recovered scanning the disk. Imagine it like a book where you ripe out the table of contents. You can’t find a chapter by looking up the page number, but you can flick through the whole book and stop when you find what you are looking for.

Securing ejabberd on Debian Wheezy (7.0) : Bind epmd to localhost (127.0.0.1)

Sat, 15 Mar 2014 17:44:14 +0000

Ejabberd is a nice and (in theory) easy to setup jabber-server. However during setup I came across some WTF’s, I want to share.

What is empd?
epmd is a small name server used by Erlang programs when establishing distributed Erlang communications. ejabberd needs epmd to use ejabberdctl and also when clustering ejabberd nodes. If ejabberd is stopped, and there aren’t any other Erlang programs running in the system, you can safely stop epmd.

Boosting Audio Output under Ubuntu Linux

Sat, 26 Oct 2013 12:18:29 +0000

I often had the problem when I wanted to watch a movie or listen to some audiofile and there was background noise I wanted to turn up the volume but it was already at 100% . I thought it should be possible to turn up the signal beyond 100% and decide by myself if the signal is clipping/distored. And there is a very easy solution for the people using pulseaudio.

Encrypted off-site backup with ecryptfs

Sun, 04 Aug 2013 23:14:17 +0000

I was looking for a method to backup my data encrypted. Of course there exist plenty of possibilities, but most of them either encrypt a container or complete partition or seemed to be complicated to setup. I did not want container or partition encryption as I fear if the media is corrupted or something goes wrong during network transfer perhaps all my data would be unaccessable for me. With file-based encryption I have almost the same risk as without encryption. Even if I loose some files to corruption I can still decipher the rest of the data.

Importing tpc-h testdata into mongodb

Fri, 28 Jun 2013 14:52:45 +0000

As written in a former post, tpc-h offers an easy possiblity to generate various amounts of testdata. Download dbgen from this website and compile it: http://www.tpc.org/tpch/

now run

./dbgen -v -s 0.1

this should leave you with some *.tbl files (PIPE separated csvfiles). Now you can use my scripts to convert them into json an import them into mongodb.
i packed already some generated files into the archive and added the header, so you don’t have to generate the tbl-files by yourself. You only have to adjust the load_into_mongodb.sh script so it loads into the correct database (if test is not ok for you).

Importing large csv-files into mongodb

Fri, 21 Jun 2013 10:47:04 +0000

I wanted to import some dummy data into Mongo-DB to test the aggregation functions. I thought a nice source would be the tpc-h testdata which can generate arbitrary volumes of data from 1 GB to 100 GB. You can download the data generation kit from the website : http://www.tpc.org/tpch/

Fix sluggish mouse in Ubuntu 12.04 LTS

Mon, 26 Nov 2012 12:32:50 +0000

For some time now i have the problem with my Dell Latitude E6510 Laptop that when I plug in a USB mouse the mouse is really slow and sluggish. Usually a reboot fixes this, but this is very inconvenient. Today I tried some googleing again and found at least a workaround to restart the usb-services without rebooting. This usually helps to fix the mouse.

Ubuntu Upgrade to 12.04 LTS -> Libreoffice not working anymore

Tue, 20 Nov 2012 23:49:38 +0000

After a update session of several hours from Ubuntu 11.04 over 11.10 to 12.04 LTS I wanted to start using libreoffice, but it terminated right after start:

$> loimpress
terminate called after throwing an instance of 'com::sun::star::uno::RuntimeException'

As root it started without problems, after some googleing and seeing the gdb-trace I found the solution to my problem. Something with the migration of the previous version config files got wrong. So I just deleted them. It is not very elegant, but worked for me and as I did not make any special settings in libreoffice for me it was not painful.

Ubuntu 12.04 Gnome Classic Panel Right-Click does not work

Wed, 15 Aug 2012 13:00:01 +0000

As I was looking for this really a long time I am reposting it:

http://askubuntu.com/questions/66414/how-to-add-panel-applets-to-classic-gnome-panel

With the new gnome and using a classic-session you have to press META + ALT + RightClick to access the panel menu. In my case META is “Alt Gr”. So try this:

Informatica 9.1 Installation could not start _AdminConsole

Wed, 08 Aug 2012 13:53:07 +0000

Installing Informatica with the installer was straightforward, but for some strange reason the adminconsole could not be started. Here the output I found in the Logfile:

INFA_HOME/tomcat/logs/node.log
 2012-08-08 12:17:45,294 ERROR [Thread 6 of 6 in DomainServiceThreadPool] [SPC_10013] Prozess für Dienst _AdminConsole konnte nicht gestartet werden.
 2012-08-08 12:27:41,524 ERROR [Thread 6 of 6 in DomainServiceThreadPool] [SPC_10013] Prozess für Dienst _AdminConsole konnte nicht gestartet werden.
 2012-08-08 12:42:07,275 ERROR [Thread 6 of 6 in DomainServiceThreadPool] [SPC_10013] Prozess für Dienst _AdminConsole konnte nicht gestartet werden.

this is not very helpful, but in the following logfile I found a clue:

Glassfish Directory Deployment (explode Ear)

Wed, 04 Jul 2012 14:12:27 +0000

Recently I was struggeling with glassfish directory deployment. Actually it is quite easy:

unzip the ear-File (eg. example.ear) to a directory without .ear
then go into this directory and unzip all war and jar files to directories named _jar and _war (only on this directory level, don’t touch the files in /lib)
now copy the folder into your domains-autodeploy-folder

For more convenience, use this script. I think it is selfexplaining.

Oracle exp export with full tns-string

Thu, 24 May 2012 08:55:07 +0000

Handling the oracle tns-names file can be a pain in the ass, especially if you don’t want to rely on it. For example you want a user to enter dynamically a connection with typical “host, port, sid, username, password” configuration. In oracle you can also use the full tns-string to connect to a database. I struggled some time finding the correct escape and quotation configuration, but finally this worked:

Getting DIGITUS-DN-70440 to work with Ubuntu 11.10 and ndiswrapper

Fri, 20 Apr 2012 18:47:52 +0000

I needed a new wlan stick for my fixed pc, as the old one had a very weak reception, so I looked a bit in the shops and found that a realtek stick with reverse-sma port + a extra large antenna just were about 15 Euros. The exact name of the stick is DIGITUS-DN-70440, but it has a Realtek 8192CU chipset on board. Thinking about the fine support for Realtek Ethernet-Cards and reading it had “Linux-Support” I thought it should work like a charm…..Screw this. The crapstick kept kicking me out of the wlan every 10 seconds and I was blaming everthing else until I realised, it’s the driver. The experience I made was: you just can’t use the linux driver…

Glassfish 3.1.1 increase asadmin deployment timeout

Thu, 01 Mar 2012 16:48:18 +0000

Recently I was wondering why the deployment of a EAR-File on Glassfish 3.1.1 over the Web-Administration-Console or with asadmin took very very long in compare to local deployment with eclipse. The EAR-File is about 50 MB of size and contains a complex web-application. With eclipse deployment takes about 20 seconds. With administration-console or with asadmin the deployment takes more than 10 minutes. As the default deployment timeout value of asadmin is 600 seconds i even wasn’t able to deploy it at all.

Gnome Panel Applets not showing up in Applet List in Ubuntu 10.4 Natty

Tue, 17 Jan 2012 13:41:17 +0000

For quite some time I was trying to figure out why my installed applets like “hamster-applet” for example where not showing up in the applet list. Finally I found the solution. You have to install the gnome applet bonobo compatibility package:

Generating MS Project Plans with MPXJ

Sun, 27 Nov 2011 22:44:01 +0000

Lately needed to create a project plan for a company who was doing some migrations. In this migrations a lot of different systems (about 200) and ressources (about 200 people) where involved. There were about 30 tasks which all had a different duration and different people involved depending on the system for which they were performed. First we thought about doing it the hard way: preparing a template for one system, copy&pasting it 200 times, then adjusting the values as needed. But due to frequent changes in the plan soon this turned out as unmanageable work effort.
So I was looking for some solution to automatically generate the plan.

nice hibernate annotation tutorial

Sun, 27 Mar 2011 20:26:13 +0000

playing around with spring and hibernate I found this very good and practical tutorial which explained to me how to model many-to-many and one-to-many relationships with hibernate using annotations.

http://www.vaannila.com/hibernate/hibernate-tutorial/hibernate-tutorial.html

By the way. If you need a good starting point for exploring spring with hibernate and maven as build system check this page out. For my tests I slightly modified the example and added the maven exec plugin to actually run the project without having to worry about the dependency libraries. (i will add this part of the pom.xml some day to this post)

Studieren oder nicht studieren, das ist hier die Frage

Sun, 27 Mar 2011 20:02:32 +0000

Schule fertig was nun?

Diese Frage stellt sich jedem Schüler am Ende seiner Schullaufbahn. So auch mir. Als ich die Schule beendet hatte, musste ich Zivildienst leisten und war darüber zunächst ganz und gar nicht glücklich über diese lästige “Wartezeit”. Im Nachhinein muss ich sagen, dass dies eine sehr wertvolle Erfahrung für mich war und mir einen Einblick in die Pflegeberufe und das Arbeitsleben ermöglicht hat. Des weiteren wird man natürlich auch mit krank sein und älter werden konfrontiert, was für die meisten Schüler nicht zu den Alltagserfahrungen gehört. Danach verbrachte ich viereinhalb Monate im Ausland was ich auch nur empfehlen kann. Das hilft enorm den ganzen Alltag einfach hinter sich zu lassen und die Welt mal mit anderen Augen zu sehen (nebenbei kann man auch noch sehr schnell und bequem eine Sprache lernen). Irgendwann ist sie dann aber doch da. Die Frage wie es nun weiter gehen soll. Ganz wichtig ist hier im Vorfeld: Erfahrungen sammeln. Wenn es die Möglichkeit gibt ein Praktikum in irgendwelchen Berufen zu machen, einen Ferien- oder Nebenjob auszuüben, das alles sind sehr wertvolle Erfahrungen und man weiß danach zumindest was man nicht machen will.