Rendering DOT Files

This week’s post is a bit more specialized than usual. DOT is famous and widely used markup language to describe graphs.

It is rare that someone is writing directly in this language. Instead, libraries are commonly used to save a graph structure in DOT format.

With the following command a valid DOT file can be rendered to a PNG picture file: dot -Tpng filename.dot -o filename.png

Essential Commands in VI/VIM

In this post I will list the absolute essential commands for the standard editor VI. Of course these commands will also work for the famous improved derivate of this editor, VIM.

  • Insert mode: i
  • Delete character: x
  • Delete line: dd
  • Mark text: v
  • Copy/cut marked text: y / x
  • Paste marked text: p
  • Save file: :w
  • Quit VI: :q

List Environment Variables on Windows

In this week’s post I will tell you how to list all environment variables in the Windows Command Prompt. This commands are not working in the Power Shell!

  1. set This lists all variables and their values.

  2. path This one lists just that PATH variable.

Changing Default Applications on Ubuntu Linux

Windows and macOS have graphical ways for changing the default programs. On Ubuntu you do it the Linux way by editing a specific file.

  1. Open this file as root with the editor of your choice:

sudo vim /usr/share/applications/defaults.list

  1. Replace all [old application].desktop with [new application].desktop. With this you change the default application for all supported file types.

Disabling the Windows Installer

This time it is all about Windows administration. In a multi-user system, restricting installation rights is desireable to keep the system safe and uncluttered.

For this, the Local Group Policy Editor is needed. It can be open by typing gpedit.msc in the Windows Start search field and by pressing Enter afterwards.

There, you have to klick yourself on the left hierarchy tree in the following way:

  1. Computer Configuration
  2. Administrative Templates
  3. Windows Components
  4. Windows Installer

After having the item/folder Windows Installer opened, select and double-click on the item Turn off Windows Installer on the right side. In the appearing window, select then Enabled on the upper left corner and click finally on OK or Apply to apply the new policy.