Category: debian

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An Alternative for the Google App Postman….

Until today I worked with the Rest-API Testing Tool Postman from Google. But this tool was making me more and more suspicious in the last time. For example, you are recently asked to sign in with a Google account. So it was time to lookout for an alternative. And finally I found Insomnia. It is open source and hosted on Github.

https://insomnia.rest/

To install the tool on Linux/Debian run:

# Add to sources
echo "deb https://dl.bintray.com/getinsomnia/Insomnia /" \
| sudo tee -a /etc/apt/sources.list.d/insomnia.list

# Add public key used to verify code signature
wget --quiet -O - https://insomnia.rest/keys/debian-public.key.asc \
| sudo apt-key add -

# Refresh repository sources and install Insomnia
sudo apt-get update
sudo apt-get install insomnia
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Maven on Debian failed with JDK 1.9 – ClassFormatError

Today I ran into a problem with Maven under Debian GNU/Linux 9 (stretch). My Debian has OpenJDK 8 as also OpenJDK 9 installed. OpenJDK 9 is my default java version. My Maven version is 3.3.9.

mvn -version
Apache Maven 3.3.9
Maven home: /usr/share/maven
Java version: 9-Debian, vendor: Oracle Corporation
Java home: /usr/lib/jvm/java-9-openjdk-amd64
Default locale: de_DE, platform encoding: UTF-8
OS name: "linux", version: "4.9.0-6-amd64", arch: "amd64", family: "unix"

The problem is, that building one of my projects results in the following ClassFormat Error:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.17:test (default-test) on project imixs-workflow-core: Execution default-test of goal org.apache.maven.plugins:maven-surefire-plugin:2.17:test failed: There was an error in the forked process
[ERROR] java.lang.ClassFormatError: Absent Code attribute in method that is not native or abstract in class file javax/xml/bind/JAXBException
[ERROR] at java.base/java.lang.ClassLoader.defineClass1(Native Method)
[ERROR] at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1007)
[ERROR] at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:174)
[ERROR] at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:801)
[ERROR] at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:699)
[ERROR] at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:622)
[ERROR] at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:580)
[ERROR] at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:185)
[ERROR] at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:496)
[ERROR] at java.base/java.lang.Class.getDeclaredMethods0(Native Method)
[ERROR] at java.base/java.lang.Class.privateGetDeclaredMethods(Class.java:3139)
[ERROR] at java.base/java.lang.Class.getMethodsRecursive(Class.java:3280)
[ERROR] at java.base/java.lang.Class.getMethod0(Class.java:3266)
[ERROR] at java.base/java.lang.Class.getMethod(Class.java:2063)
[ERROR] at org.apache.maven.surefire.util.ReflectionUtils.tryGetMethod(ReflectionUtils.java:57)
[ERROR] at org.apache.maven.surefire.common.junit3.JUnit3TestChecker.isSuiteOnly(JUnit3TestChecker.java:64)
[ERROR] at org.apache.maven.surefire.common.junit3.JUnit3TestChecker.isValidJUnit3Test(JUnit3TestChecker.java:59)
[ERROR] at org.apache.maven.surefire.common.junit3.JUnit3TestChecker.accept(JUnit3TestChecker.java:54)
[ERROR] at org.apache.maven.surefire.common.junit4.JUnit4TestChecker.accept(JUnit4TestChecker.java:52)
[ERROR] at org.apache.maven.surefire.util.DefaultScanResult.applyFilter(DefaultScanResult.java:97)
[ERROR] at org.apache.maven.surefire.junit4.JUnit4Provider.scanClassPath(JUnit4Provider.java:206)
[ERROR] at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:103)
[ERROR] at org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:200)
[ERROR] at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:153)
[ERROR] at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:103)
[ERROR] -> [Help 1]

The problem is a incompatibility of maven 3.3.9 with JDK 1.9. To solve this problem I switch to my OpenJDK 8 by setting the JAVA_HOME variable explicitly to JDK8 :

export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64/

After this change maven install works fine again in my projects.

To make the JAVA_HOME setting permanent follow this stepts.

1. find your preferred java version

ls -la /usr/lib/jvm/

2. edit the file /etc/profile and add the following line with the path to the JDK 8 you find before:

export JAVA_HOME="path to jdk8 that you found"

3. verify you maven installation

mvn -version

You maven should now be set to JDK8.

I hope this post will become obsolete in near future.

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Debian – user Bluetooth Speackerbox with Micro

Today I tried to connect a “August MS425” speaker box with my Linux Notebook running on Debian Jessie. To get the bluetooth connection running I installed the following additional packages:

sudo apt-get install pulseaudio-module-bluetooth, ofono, pavucontrol

After I established the bluetooth connection the speaker box was not working or displayed in the list of audio devices. To solve this issue I found this discussion.

The missing part was the the auto-connect a2dp option for the new device. So I had to edit the file “/etc/pulse/default.pa” and added the following line :

load-module module-switch-on-connect

After a reboot it works fine. You can use pavucontrol to setup audio settings.

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VirtualBox no longer running in Debian

Today I had a strange problem with virtualbox in Debian Jessie which was no longer running.  When I start a virtual machine I got the following error message

The VirtualBox Linux kernel driver (vboxdrv) is either not loaded or
there is a permission problem with /dev/vboxdrv. Please reinstall the
kernel module by executing

'/etc/init.d/vboxdrv setup'

But the problem was that the vboxdrv was not installed so I was unable to run that command. Alos reinstalling Virtualbox or the linux-headers did not solve the problem.

After all I found this discussion on stackoverflow.  I was able to solve the problem by installing a new version of Virtualbox from the backports by using the following command:

apt-get -t jessie-backports install virtualbox

 

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Debian – Laptop Power Calibration

Since 2 years I have a Wortmann Ultrabook running on Debian. Since some weeks the the battery life has deteriorated sharply. I found this helpful article about the linux tool ‘powertop’.  You can use this tool to recalibrate the battery of a loptop using the following command:

sudo powertop --calibrate

At a first look it seems like this helped much to improve the power management of my laptop.

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Linux Debian and Skype – no microphone

Today I had a strange problem with my skype installation in Debian. The microphone seems not to work. Finally I found the solution here.

The trick is the following:

  1. Open the Sound settings when you start a skype test call.
  2. Click on the tab ‘Recourding’
  3. Choose the option : show ‘all streams’ at the bottom of the tab
  4. Now when the skype call runs you will see the skype application appearing
    skype_audio
  5. There is a tiny button muting the microphone. This option was selected in my case. Deselecting the mute button solved the problem for me
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Eclipse Luna crashes on Ubuntu

Today I had strange problems with Eclipse Luna after an Ubuntu Update.
The solution was changing the eclipse.ini by adding

-Dorg.eclipse.swt.browser.DefaultType=mozilla

and changing the memory settings.
Thanks to Bård Aase Blog: http://blog.elzapp.com/2014/07/01/making-eclipse-kepler-and-luna-work-on-ubuntu.html

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Debian – gdm3 and Gnome broken after dist-upgrade

Yesterday I upgraded my debian testing release (jessie) and after that the Gnome Desktop and also gdm3 (the Desktop Manager to login) was broken. I installed lightdm and xfce to get back a working desktop. But I can’t figure out whats going wrong until my last upgrade.

Finally I found help in this forum thread.

So I removed all the nvidia packages (I had no nvidia graphic card but a Intel HD3000)

apt-get remove --purge nvidia-*

Next I reinsalled gdm3, gnome and reconfigured finally gdm3

apt-get --reinstall install gdm3
apt-get --reinstall install gnome
apt-get --reinstall install gnome-shell
dpkg-reconfigure gdm3

After that procdure my system worked again!

I don’t understand why a dist-upgrade on a system with not nvidia graphic card leads into such a strange situation.

Corrupted /tmp folder

Additional I was affected from a corrupted /tmp folder which shows the wrong size. To solve this I found the following Blog Post.

http://deshack.net/debian-hangs-during-boot/

  1. press ‘e’ during the grub boot loader
  2. add the following to the end of the line starting with /boot/vmlinuz…
    –add rw init=/bin/bash
  3. press f10 to boot with that configuration – system will start in a bash
  4. remove and create the tmp folder
    >rm -rf /tmp
    >mkdir /tmp
    >chmod  1777 /tmp
  5. reboot system

This helps me to create a new empty /tmp folder.

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