Samsung Galaxy A8 (2018) Android 9, TWRP, Magisk root

Here is the guide I’ve used to install Android 9 (pie), TWRP and root (using Magisk). That guide is pretty accurate, though SuperSU v2.82 SR5 (the latest I could find) didn’t work. Instead Magisk v18.1 does work for rooting :).

Device: Samsung Galaxy A8 (2018), SM-A530F.


Here is a list of software (and version numbers) that works for me:

  • MagiskManager-v7.0.0.apk
  • (🇳🇱 no carrier)
  • twrp-3.2.3-0-jackpotlte.img.tar

Optional for unrooting:


Too bad JOdin didn’t recognize the phone, and I had to use Odin on Windows:

  • SAMSUNG_USB_Driver_for_Mobile_Phones.exe

I’ve had no issues with ‘missing OEM unlock toggle‘ (and having to wait seven days to unlock). Hope this helps to quickly setup Android 9, TWRP and to unlock the phone. Have fun, all credits go to the devs at XDA.


jconsole fatal startup error

Upon starting jconsole I was greeted by the following error:

eimert@EIM ~ $ jconsole
# A fatal error has been detected by the Java Runtime Environment:
# SIGSEGV (0xb) at pc=0x00007f572fdf0009, pid=31852, tid=31924

It seems jconsole is running on Java 9 while IntelliJ is using Java 8. Here’s how to fix it.

eimert@EIM ~ $ jconsole
# A fatal error has been detected by the Java Runtime Environment:
# SIGSEGV (0xb) at pc=0x00007f572fdf0009, pid=31852, tid=31924
# JRE version: OpenJDK Runtime Environment (9.0) (build 9-internal+0-2016-04-14-195246.buildd.src)
# Java VM: OpenJDK 64-Bit Server VM (9-internal+0-2016-04-14-195246.buildd.src, mixed mode, tiered, compressed oops, g1 gc, linux-amd64)
# Problematic frame:
# C [] JNU_GetEnv+0x19
# No core dump will be written. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
# An error report file with more information is saved as:
# /home/eimert/hs_err_pid31852.log
# If you would like to submit a bug report, please visit:
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.

jconsole is a symlink to /etc/alternatives/jconsole:

eimert@EIM ~ $ which jconsole
eimert@EIM ~ $ ll /usr/bin/jconsole
lrwxrwxrwx 1 root root 26 apr 6 2018 /usr/bin/jconsole -> /etc/alternatives/jconsole

Fixed that startup error by using jconsole from java 8:

eimert@EIM ~ $ sudo update-alternatives --config jconsole
Er zijn 2 beschikbare keuzemogelijkheden voor het alternatief jconsole (dat voorziet in /usr/bin/jconsole).

Keuze Pad Prioriteit Status
0 /usr/lib/jvm/java-9-openjdk-amd64/bin/jconsole 1091 automatische modus
* 1 /usr/lib/jvm/java-8-openjdk-amd64/bin/jconsole 1081 handmatige modus
2 /usr/lib/jvm/java-9-openjdk-amd64/bin/jconsole 1091 handmatige modus

Druk om de huidige keuze[*] te behouden, of typ een keuzenummer in:

jconsole boots:

What it is like to be an infra developer at ING

This blogpost inspired me to write about the (infra) tech stack at ING.

What are the most common tools that developers use at ING?
In general, every infra developer uses Git, Gitlab, Gitlab-CI, Ansible, Jenkins, Lync, Atlassian tooling and Service Now. Developers choose their own IDE.


I frequently use these tools:

  • Royal TS (terminal emulator)
  • vim
  • Sublime Text
  • IntelliJ IDEA
  • Lots of terminal tools for text mangling
  • Meld


Which languages do developers code in?
Primarily Ansible. Other languages are shell scripting languages, Python, JavaScript, .Net, Groovy, Power Shell.

What is the development process like? (the life cycle of a piece of committed code)?
It varies per team. Generally, code is being checked in after running unit tests. Code is peer-reviewed before merging with master. Once comments are addressed, the merge request is approved and merged into master. Merges into the master branch trigger a build pipeline. New pipelines automatically deploy to production.

What is code review like?
A colleague checks if the code conforms to our Definition of Done (DoD) and acceptance criteria specified in the story. There is a peer-review to assess the impact on production from different angles.

How is testing done, and what kind of tests are run?
We currently use the goss test framework for infra code. I’ve seen teams that have built extensive automated test pipelines. Teams are encouraged to build the test automation they deem necessary. There are test VM’s available that are rebuild every night.

How is code deployed?
Mostly through pipelines built in Jenkins or Gitlab-CI.

What is an average day-in-the-life of someone on one of the development teams?
Most teams are working in sprint cycles of two weeks. Team members may choose to work from home. I’d say time is spend on engineering activities, experimenting, learning, meetings, operational support, and other activities.

Colleagues go to lunch together, there are lunch talks, and some go running during lunchtime. ING provides a weekly boot camp training after work. Or go for drinks after work.

What makes ING a special place to be a developer?
At ING you get to work at a recognizable brand. Teams at ING are working on continuous improvement of their processes. At ING you get to work with new exiting technology on a large scale.

Can you tell us a bit about your team and what you are working on?
I’m working with my team to provide Tomcat within the ING. We make sure Tomcat is offered free of vulnerabilities, integrates with deployment tooling, and conforms to rules and regulations. I like to keep in mind that most of the back-end of web and mobile runs on Tomcat.

Infrastructure as code met terraform en azure

I’ve made and presented this IaC presentation back in 2016. Note: in Dutch.


Summary of the presentation
It gives a smooth introduction to Infrastructure as Code. Has a overview of cloud agnostic IaC tooling. Gentle demo of Terraform, a great tool for CRUD-operations on cloud resources. Terraform supports many cloud providers. IaC adds the benefits of version control to infra code. IaC is building up maturity. The impact of changes to infra can be difficult to determine.

More on IaC

jobflirt #2 at Java DevOps team

I managed to arrange a second jobflirt, this time at a Java DevOps team. The team is providing a popular online payment method in The Netherlands.

Besides online payments, the team provides:

  • iDIN (digital identification),
  • eMandates (customer authorization for direct debits),
  • and other (future) services.


My intention is to apply my Java programming skills in practice within a real team, working on an actively used application. And I’m looking for feedback to become a great engineer.


I’ve completed a few stories, writing code that is now running in production. I’m really content with the results we have delivered. Thanks to the excellent colleagues at the team, the code got reviewed fast, with good remarks. The agile rituals of the team have inspired me. I’ve got new, fresh pointers to books and practice materials to become proficient in Java.


Another successfully completed jobflirt that was mutually beneficial to both parties.

work/life/career must-read books

These are the books I’ve read or want to read. I can really recommend to go deep into the subject of personal development. Most of what I’ve read can easily be applied in everyday life :). Or sets into motion subconscious changes.

John Somnez (

Credits: book suggestions from Martin Koel.


Book: team geek


If you were to ask me to summarize the book ‘Team Geek‘ into one key point, it would be this:

“Great software is build by teams”.

Therefore modern workplaces are hubs where developers collaborate and build upon each others’ knowledge.

Functioning in a team boils down to having ‘HRT’ (hearth):

  • Humility
  • Respect
  • Trust
HRT. Source:

And to be an effective engineer, communication is vital.


big leap in personal development

Recently I started with a job flirt at work. It is a funky name for ‘experiencing what it is like to work for another team’. Next up there is more on my ‘big leap in personal development’.

I started at the TUX-team. I wanted to experience the engineering spirit within that team, and to get feedback on my soft skills.

The end?

After two sprints (four weeks) it was time to go back to my original squad. I enjoyed the job flirt. I exceeded others’ expectations of my soft skills. How did I do this?


Well, I’ve been meditating. Through meditation, I learned to be more patient and relaxed. And when I’m relaxed, that benefits others too. I’m easier to get along with, easier to approach and to collaborate with.

I started meditating on a daily basis eight months ago. I’m using Headspace guide meditations. Andy has done a great job by offering a Westernized approach to meditation.


Other credits go to the book ‘verbinding door avontuur’. Floor Vullings and Floris Muller have published this long awaited book about the ‘buitendoor‘ approach to team building and collaboration. It was refreshing to read and I could directly apply the material at the job flirt.


Website :
ISBN        : 9789082823400