How to install Celestia in Ubuntu 18.04 or Debian 9

Latest Debian based distros don't include Celestia in their repositories and you need to compile the software to enjoy it.

Just need to type the following commands in your console (Ubuntu and derivates distros):

sudo apt-get install libglew-dev libjpeg-dev libpng-dev libtheora-dev libgl1-mesa-dev libeigen3-dev libfmt-dev qtbase5-dev qtbase5-dev-tools and libqt5opengl5-dev freeglut3-dev libgtkglext1-dev liblua5.2-dev git
git clone https://github.com/CelestiaProject/Celestia
cd Celestia/
mkdir build
cd build/
cmake .. -DENABLE_QT=ON
make
sudo make install

If you use Debian type first su - and then type the same commands as Ubuntu case but don't type sudo

How to compile and install povray in Ubuntu, Debian and distro derivates

Povray is a ray tracer available for several systems, although on unix systems you need to compile it, but it's easy following these steps:

Compile and install

Install the libraries you need to compile:

sudo apt-get install zlib1g-dev libpng12-dev libjpeg-dev libtiff5-dev libopenexr-dev libsdl1.2-dev libboost-system1.55-dev libboost1.55-dev git

Download the latest source code:

git clone https://github.com/POV-Ray/povray.git povray

Compile and install:

cd povray/unix
./prebuild.sh
cd ..
./configure COMPILED_BY="your name" LIBS="-lboost_system -lboost_thread"
make
sudo make install

Now, povray is installed in your computer.

Note: You needn't LIBS="-lboost_system -lboost_thread" in Debian.

How to use

You can generate a Full HD image with this command:

povray -W1920 -H1024 file.pov

Pov file is a text file with all the instructions in povray language to render a image (may be a very big file).

You can get amazing images like this:

Shortcuts in Debian LXDE

Desktop shortcuts are very useful to order your favorite software.

There is two ways to make shortcuts in LXDE:
 

Clone shortcuts from start menu

1. Press start menu
2. Select the category
3. Right click on item we want to clone.
4. Select option 'Add to desktop'.

Made icons from scratch

• Open the console (Start => Accessories => LXTerminal).
• Select the Desktop folder
  cd Desktop
• Create a file with a name similar to my_app.desktop with this content:
  [Desktop Entry]
Version=1.0
Encoding=UTF-8
Name=Name_of_the_app
Comment=Comments_about_the_app
Exec=exec_file
Path=path_to_exec_file
Icon=path_to_icon
Type=Application
Categories=Categories_separate_with_semicolon;

• This file must have writing rights for the owner than must be the user.sudo chmod +x my_app.desktop

Compiling LeoCAD in any GNU/Linux

LeoCAD is a LDraw file editor, a open format to make LEGO(R), TENTE(R), EXIN CASTILLOS(R), etc... virtual models.

I follow this steps to compile Leocad:

1. Install subversion and the necesary libraries to compile QT code:
   sudo apt-get install git libqt4-dev zlib1g-dev
2. Download the lastest version of code in a folder, for example $HOME
   cd $HOME
git clone https://github.com/leozide/leocad/
3. Change to this directory, compile and install:
   cd leocad
qmake leocad.pro
make
sudo make install 
4. If we use the LEGO library we might launch the software with this command (I suppose you download the library in /opt/ldraw/lego):
   leocad -l /opt/ldraw/lego/

You can also use the Tente® 3D library, then the comand to run might be:
leocad -l /opt/ldraw/tente
If you compile in a raspberry pi, use qmake-qt4 leocad.pro instead of qmake leocad.pro.

Original articles

• Tente 3D en Raspberry pi 2 (I): compilando LeoCAD.
• LeoCAD en Ubuntu 14.04 LTS de 64 bits.
• LeoCAD en Ubuntu (II): configuración para Tente 3D.

How to autologin on Debian 9 (Stretch)

Autologin means than when Debian runs a session starts without entering any password.

This is very comfortable, but it implies a security risk because if someone has access to our computer can access its content, so it would be very interesting for a public computer without personal data for generic use but not for a laptop for example.

In any case if we access by network, for example by ssh, the system will continue asking for the password.

To get this in Debian Stretch we modify the /etc/lightdm/lightdm.conf file and change the lines:

#autologin-user=
#autologin-user-timeout=0

for:

autologin-user=your_user
autologin-user-timeout=0

Simple and fast.