Here is a shortlist of introductory tutorials and materials to learn the basics of programming in popular scripting languages.


Getting Started with Python
If you don’t have any knowledge of Python, what you need to know is here. In about fifteen tutorials, you will become familiar with the most notable features of the language and be able to write Python programs for most of your needs.

Pandas Python tutorials
10 Truly "getting started" tutorials on using Pandas to manipulate large data frames in Python. Limited knowledge of Python is required. When advanced notion are used, they are clearly identified to avoid beginner readers to be lost. Each tutorial ends with a concise « Remember » section, pinpointing the most important notions of the tutorial.

Check out also: Pandas Python cookbook


R programming on Coursera
Nice and comprehensive introduction to R, from installation to all the basics. Total duration ~4h30' (Videos in Week 4 can be skipped).

R handbooks in PDF (for intermediate user):


Bash scripting for beginners
Simple tutorial covering the basics of navigating the terminal and bash scripting. I would recommend it until the chapter "Variables" (included).