elementary OS – Puppy Chau

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

Go to the All .NET Download site of Microsoft at https://www.microsoft.com/net/download/all.
Click the link to the SDK version you want. For example, 2.1 SDK (v2.1.301) downloads.
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.

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 https://packages.microsoft.com/config/ubuntu/16.04/packages-microsoft-prod.deb
--2018-06-27 11:03:08--  https://packages.microsoft.com/config/ubuntu/16.04/packages-microsoft-prod.deb
Connecting to 10.0.2.2:3128... 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 http://aka.ms/dotnet-cli-eula for more information.
Welcome to .NET Core!
---------------------
Learn more about .NET Core: https://aka.ms/dotnet-docs
Use 'dotnet --help' to see available commands or visit: https://aka.ms/dotnet-cli-docs

Telemetry
---------
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: https://aka.ms/dotnet-cli-telemetry

Configuring...
--------------
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
2.1.301

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.

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.
Change directory to install the JDK code in /opt
```
cd /opt
```
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
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" 
```
Refresh the environment variable.
```
source /etc/environment
```

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

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)

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)

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

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

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: https://bugzilla.gnome.org/show_bug.cgi?id=85715
For details, see etc/PROBLEMS.
Fatal error 6: Aborted
Backtrace:
emacs[0x4f74cb]
emacs[0x4dcf3e]
emacs[0x4f7513]
emacs[0x4b219b]
emacs[0x4b420c]
emacs[0x4b426d]
/usr/lib/x86_64-linux-gnu/libX11.so.6(_XError+0x12b)[0x7f78f57b654b]
/usr/lib/x86_64-linux-gnu/libX11.so.6(+0x3b5e7)[0x7f78f57b35e7]
/usr/lib/x86_64-linux-gnu/libX11.so.6(+0x3b695)[0x7f78f57b3695]
/usr/lib/x86_64-linux-gnu/libX11.so.6(_XReply+0x1e8)[0x7f78f57b4578]
/usr/lib/x86_64-linux-gnu/libX11.so.6(+0x325e0)[0x7f78f57aa5e0]
...
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:

XLIB_SKIP_ARGB_VISUALS=1 emacs

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.