Installing Scala IDE for Eclipse
Scala IDE can be installed as an Eclipse plugin.
To install Eclipse go here: Installing Eclipse IDE on Linux

Installation
Start Eclipse. Note Eclipse version visible on splash screen (e.g. Eclipse Kepler ).
Go to Help menu (top right) and click on Install New Software...
Click on Add... button (top right).
In Name box enter Scala IDE (ar anything you want). Leave this menu open.

Get Eclipse update URL for Scala IDE plugin
Open this link in your browser: scala-ide.org/download/current.html
Scroll down until you see the plugin version corresponding to your Eclipse version (e.g. Eclipse 4.3 (Kepler) ).
Copy the URL visible there (black text on green background, e.g. http://download.scala-ide.org/sdk/helium/e38/scala210/stable/site ) into clipboard (select, press Ctrl + C).

Go back to open Eclipse menu, paste the text you copied into Location box (Ctrl + V). Click OK .

Select the first check box ( Scala IDE for Eclipse ), click Next . On the second screen click Next again.

Select I accept the terms of the license agreements radio button, click Finish .
Download should start, the title should say Installing software .

If you get a message saying something like You are about to install unverified packages just click OK (optional).
Eclipse will ask you for a restart, click Restart now .

After Eclipse restarts you should see a message saying Upgrade of Scala plugin detected . Click Yes .

You can leave all settings on default values, except for memory settings. Scala plugin is a bit memory intensive and your Eclipse may crash if heap memory is exhausted.
If you see this message: Warning: recommended value is at least 1024M you might consider increasing Eclipse heap size.
See section Update Eclipse memory settings of this document: Installing Eclipse IDE on Debian Linux on how to do that (increase value of the Xmx property).
If your computer has enough memory I would recommend setting -Xmx2048m .

Now you can write Scala code in Eclipse. If you do not see Scala perspective open Window/Open Perspective(optionally /Other) menu and click on Scala .
To create a new Scala project right click on empty space in Package Explorer window (left) and select New/Scala Project .