Category: Linux

Using Multiple Desktops in Raspbian Jessie

✎ Last updated on 2020-01-29 at 13:01 EST

To set up multiple desktops:

  1. Click Menu
  2. Click Preferences
  3. Click Openbox Configuration Manager
    menu to Openbox Configuration Manager
    Menu to obconf

     

    If you do not see the Openbox Configuration Manager, install it by running:
    sudo apt-get install -y obconf

  4. Click on the Desktops tab, and select the desired Number of desktops.

    Desktop Settings
    Desktop Settings

You now have multiple desktops, use the keyboard shortcuts Ctrl + Alt + ⇨ or Ctrl + Alt + ⇦ to switch between the next and previous desktop.

If the shortcuts keys do not work, refer to the following post for Raspbian keyboard shortcuts to change your key-binding in Openbox.

Location of Raspbian Jessie keyboard shortcuts

✎ Last updated on 2017-12-20 at 15:40 EST

The default keyboard shortcut setting is in the file
/etc/xdg/openbox/lxde-pi-rc.xml
under the <keyboard> section.

There may also be an rc.xml setting file in the same folder for your reference

Your personal shortcuts, if they exists, is in
~/.config/openbox/lxde-pi-rc.xml

For examle, add the following in the <keyboard> section to move to adjacent desktop workspace

<keybind key="C-A-Left">
  <action name="DesktopLeft"/>
</keybind>
<keybind key="C-A-Right">
  <action name="DesktopRight"/>
</keybind>

Installing Node.js on Linux from Binaries

  1. Download Node.js binaries

    Node.js binaries are available at nodejs.org. You can download the more stable LTS version or Current version with the latest features.

  2. Extract the download binary files

    You can either first extract the binary files to a temporary directory, then copy them to the /usr/local directory; or extract the files right into the /usr/local directory.

    1. Extract to temporary folder, and then copy the files to /usr/local folder.

      # cd temp
# tar -xvJf ~/downloads/node-v7.2.0-linux-x64.tar.xz
# cd node-v7.2.0-linux-x64
# sudo cp -R . /usr/local
    2. Extract directly into the /usr/local folder. First change directory to /usr/local, and then issue the tar command.

      # sudo tar --strip-components=1 -xvJf ~/downloads/node-v7.2.0-linux-x64.tar.xz
  3. Check Node.js installation
    # node -v
v7.2.0
  4. Check npm installation
    # npm version
{ npm: '3.10.9',
  ares: '1.10.1-DEV',
  cldr: '30.0.2',
  http_parser: '2.7.0',
  icu: '58.1',
  modules: '51',
  node: '7.2.0',
  openssl: '1.0.2j',
  tz: '2016g',
  unicode: '9.0',
  uv: '1.10.1',
  v8: '5.4.500.43'
  zlib: '1.2.8' }

apt-get Behind a proxy server that requires authentication

Create a new file in the /etc/apt/apt.conf.d

for example: create the file 80proxy with

sudo nano /etc/apt/apt.conf.d/80proxy

and add the following lines to configure the proxy setting:

Acquire::http::Proxy "http://<username>:<password>@<proxy IP>:<port>";

Acquire::https::Proxy "http://<username>:<password>@<proxy IP>:<port>";

Acquire::ftp::Proxy "http://<username>:<password>@<proxy IP>:<port>";

Install Oracle JDK 10.0.1 on Linux

✎ Last updated on 2018-05-15 at 12:30 EDT

[Updated for jdk-10.0.1]
This is for 64-bit installation.

  1. Download JDK from Oracle site
    http://www.oracle.com/technetwork/java/javase/downloads
    The installation file I use is jdk-10.0.1_linux-x64_bin.tar.gz.
  2. Change directory to install the JDK code in /opt 
    cd /opt
  3. extract the JDK files 
    sudo tar -xvzf <location of downloaded JDK>/jdk-10.0.1_linux-x64_bin.tar.gz

    This will put the JDK into the newly created directory named jdk-10.0.1

  4. Update environment variables to point to the newly installed JDK by editing the /etc/environment file. 
    sudo nano /etc/environment

    Add the JAVA_HOME variable, and add JDK bin to the PATH variable.

    JAVA_HOME="/opt/jdk-10.0.1"
PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/opt/jdk-10.0.1/bin"
  5. Refresh the environment variable. 
    source /etc/environment
  6. Verify that the updated environment variables are in place and the path to the JDK is valid 
    $ echo $JAVA_HOME
/opt/jdk-10.0.1
$ echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/opt/jdk-10.0.1/bin
  7. Update Java alternative list. You want to set a higher priority for the new JDK. On my system this is the result when I query the alternatives: 
    $ update-alternatives --verbose --query java
Name: java
Link: /usr/bin/java
Slaves:
 java.1.gz /usr/share/man/man1/java.1.gz
Status: auto
Best: /usr/lib/jvm/java-9-openjdk-amd64/bin/java
Value: /usr/lib/jvm/java-9-openjdk-amd64/bin/java

Alternative: /usr/lib/jvm/java-9-openjdk-amd64/bin/java
Priority: 1091
Slaves:
 java.1.gz /usr/lib/jvm/java-9-openjdk-amd64/man/man1/java.1.gz

    So, let’s make the new JDK our default…

    sudo update-alternatives --install /usr/bin/java java /opt/jdk-10.0.1/bin/java 10001

    The response is:

    update-alternatives: using /opt/jdk-10.0.1/bin/java to provide /usr/bin/java (java) in auto mode.

    Now, when you type java -version, you will see

    java version "1.0.1" 2018-04-17
Java(TM) SE Runtime Environment 18.3 (build 1.0.0.1+10)
Java HotSpot(TM) 64-Bit Server VM 18.3 (build 10.0.1+10, mixed mode)
  8. Likewise, set the new Java compiler as default with

    $ sudo update-alternatives --install /usr/bin/javac javac /opt/jdk-10.0.1/bin/javac 10001
update-alternatives: using /opt/jdk-10.0.1/bin/java to provide /usr/bin/javac (javac) in auto mode
$ javac -version
java version "10.0.1" 2018-04-17
Java(TM) SE Runtime Environment 18.3 (build 10.0.1+10)
Java HotSpot(TM) 64-Bit Server VM 18.3 (build 10.0.1+10, mixed mode)
  9. If you wish, you can remove the link to the older java alternative 
    $ sudo update-alternatives --verbose --remove java /usr/lib/jvm/java-9-openjdk-amd64/bin/java
update-alternatives: discarding obsolete slave link java.1.gz (/usr/share/man/man1/java.1.gz)
$ update-alternatives --verbose --query java
Name: java
Link: /usr/bin/java
Status: auto
Best: /opt/jdk-10.0.1/bin/java
Value: /opt/jdk-10.0.1/bin/java

Alternative: /opt/jdk-10.0.1/bin/java
Priority: 10001
  10. In the similar way, remove the old javac alternative link. 
    $ update-alternatives --verbose --query javac
Name: javac
Link: /usr/bin/javac
Slaves:
 javac.1.gz /usr/share/man/man1/javac.1.gz
Status: auto
Best: /opt/jdk-10.0.1/bin/java
Value: /opt/jdk-10.0.1/bin/java

Alternative: /opt/jdk-10.0.1/bin/java
Priority: 10001
Slaves:

Alternative: /usr/lib/jvm/java-9-openjdk-amd64/bin/javac
Priority: 1091
Slaves:
 javac.1.gz /usr/lib/jvm/java-9-openjdk-amd64/man/man1/javac.1.gz
$ sudo update-alternatives --remove javac /usr/lib/jvm/java-9-openjdk-amd64/bin/javac