Install .NET Core SDK on elementary OS

At this writing, I’m running elementary OS 0.4.1 Loki, which is based on Ubuntu 16.04.2 LTS. (It is important to know the Ubuntu version, since the .NET Core SDK distribution has different source list for different Linux distros and versions.)

.NET Core SDK version: v2.1.301

  1. Go to the All .NET Download site of Microsoft at
  2. Click the link to the SDK version you want. For example, 2.1 SDK (v2.1.301) downloads.
  3. Choose the link of the Linux distro and version you are using. For example, since I’m running elementary OS, I click on the Ubuntu 14.04 Instructions link.
  4. Follow the instruction on the page to register Microsoft key and repository, and to follow steps to install .NET SDK.

    In my case, since my connection to the internet is behind a proxy server, I first make sure that wget is using proxy (see this post about [wget proxy setting]).

    Register Microsoft key and package source

    I type in the following wget command to get the .deb package from Microsoft.

    ~$ wget
    --2018-06-27 11:03:08--
    Connecting to connected.
    Proxy request sent, awaiting response... 200 OK
    Length: 2452 (2.4K) [application/octet-stream]
    Saving to: ‘packages-microsoft-prod.deb’
    packages-microsoft-prod.deb                                 100%[==========================================================================================================================================>]   2.39K  --.-KB/s    in 0s      
    2018-06-27 11:03:09 (469 MB/s) - ‘packages-microsoft-prod.deb’ saved [2452/2452]

    I then install the downloaded package

    ~$ sudo dpkg -i packages-microsoft-prod.deb
    Selecting previously unselected package packages-microsoft-prod.
    (Reading database ... 173634 files and directories currently installed.)
    Preparing to unpack packages-microsoft-prod.deb ...
    Unpacking packages-microsoft-prod (1.0-3) ...
    Setting up packages-microsoft-prod (1.0-3) ...

    Which does three things: 1) adds the Microsoft packages information to the source list; 2) adds the Microsoft key to the trusted list; and 3) sets root as the owner of the two added files. See directory listing below:

    ~$ ls -l /etc/apt/sources.list.d/
    total 16
    -rw-r--r-- 1 root root  56 Feb 14 10:56 appcenter.list
    -rw-r--r-- 1 root root 144 Feb 14 10:56 elementary.list
    -rw-r--r-- 1 root root  78 Nov 27  2017 microsoft-prod.list
    -rw-r--r-- 1 root root 152 Feb 14 10:56 patches.list
    ~$ ls -l /etc/apt/trusted.gpg.d
    total 4
    -rw-r--r-- 1 root root 641 Jan 23  2017 microsoft-prod.gpg

    Install .NET Core SDK

    Make sure that https download transport for APT is installed and up to date.

    ~$ sudo apt-get install apt-transport-https

    downloads the package lists from the repositories and updates them to get information on the newest versions of packages and their dependencies.

    ~$ sudo apt-get update

    Install .NET SDK Core 2.1

    ~$ sudo apt-get -y install dotnet-sdk-2.1

    At the end of the installation, you will see the following information…

    This software may collect information about you and your use of the software, and send that to Microsoft.
    Please visit for more information.
    Welcome to .NET Core!
    Learn more about .NET Core:
    Use 'dotnet --help' to see available commands or visit:
    The .NET Core tools collect usage data in order to help us improve your experience. The data is anonymous and doesn't include command-line arguments. The data is collected by Microsoft and shared with the community. You can opt-out of telemetry by setting the DOTNET_CLI_TELEMETRY_OPTOUT environment variable to '1' or 'true' using your favorite shell.
    Read more about .NET Core CLI Tools telemetry:
    A command is running to populate your local package cache to improve restore speed and enable offline access. This command takes up to one minute to complete and only runs once.

    Verify that .NET Core 2.1 is installed

    ~$ dotnet --version

Install Oracle JDK 10.0.1 on Linux

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

  1. Download JDK from Oracle site
    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.

  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
    $ echo $PATH
  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
     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
     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
    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
     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
    Alternative: /usr/lib/jvm/java-9-openjdk-amd64/bin/javac
    Priority: 1091
     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

Changing Display Font in elementary OS’s pantheon Terminal

Edit the font property in the org.pantheon.terminal.settings schema. For example:

gsettings set org.pantheon.terminal.settings font 'DejaVu Sans Mono'

Then close and reopen the terminal for the change to take effect.

You can find the correct font name with the following command:

fc-list | cut -f2 -d: | sort -u

GNU Emacs error on elementary OS

Problem: GNU Emacs-24 crashes at startup on elementary OS. This is due to incompatibility between the graphical toolkit used in the Emacs package.

X protocol error: BadMatch (invalid parameter attributes) on protocol request 139
When compiled with GTK, Emacs cannot recover from X disconnects.
This is a GTK bug:
For details, see etc/PROBLEMS.
Fatal error 6: Aborted
Aborted (core dumped)

Solution: Setting the environment variable XLIB_SKIP_ARGB_VISUALS=1 allows Emacs to start. So use this command line to start Emacs in the terminal:


Or better yet, create a launcher in ~/.local/share/applications by copying the emacs24.desktop file, and change the Exec line to

Exec=/usr/bin/env XLIB_SKIP_ARGB_VISUALS=1 /usr/bin/emacs24 %F

See [Adding Desktop Entries to System] for more information on desktop files.