A Linux shell is a command line interpreter that provides a user interface for a system itself. It can be used to install programs (apt-get install) or even for some programming, including conditions, logic, or loops. Linux provides many different shells. Very often, the Bourne shell is used, which was developed in the 70s by Stephen R. Bourne. This shell provides input and output redirection, pipes, background processes, and much more. For all Linux systems, a Bourne-compatible shell in the /bin/sh directory is available.

It is true that nearly no other interpreter language is as popular as Python. Additionally, there are a bunch of add-ons for Python that are available, ranging from a simple web server to complex graphics libraries. In this section, the reader will learn some basics of Python. We will use Python in order to program GPIO pins. We will look at a more complex example that will deal with graphical output in a window.

sudo apt-get install python python-dev

Most Banana Pro programs found on the Internet are C/C++ programs. The main reasons for this are speed critical applications: interpreters, such as Python, are much slower compared to compiled programs such as C/C++ ones. In this section, we will have a closer look at the Linux C/C++ compiler called GNU Compiler Collection (GCC). GCC includes frontends for both the C and C++ compiler as well as libraries for these languages. We install the C and C++ compiler with the following command:

sudo apt-get install gcc g++ make

Additionally, we install make, a utility that helps the compiling and linking of C/C++ files. We again start with a very simply "Hello world!" example, which we call hello.c:

nano hello.c

We can then add the following content:

#include <stdio.h>

int main(void)
{
    puts("Hello world!");
    return 0;
}

In the preceding example, we include standard input/output headers (stdio.h). The main entry point of the program has no arguments (void) and...

Scratch is a programming language for children and teenagers. Graphical boxes have replaced all programming elements within this language. The language itself was invented and developed at MIT. The name is related to a scratching technique from turntables (mixing sounds). Scratch programs are event-driven with objects called sprites. Sprites can be either drawn or imported from external sources such as webcams.

Scratch can be used from a web interface. In addition to this, there is an Integrated Development Environment (IDE) available, which can be installed on Banana Pro using this command:

sudo apt-get install scratch

On many distributions, Scratch is already preinstalled.

Figure 13

Typing the scratch command will start Scratch, as shown in the preceding screenshot. The IDE is split into three different parts: the left-hand side column contains all programming elements, the middle area can be used to place the programming elements in order to program functionality, and the right...

All Banana Pro operating systems have a kernel installed. Depending on OS functionality, such as multimedia or GPIO usage, different kernels may be used. Usually, kernel sources are not installed. However, in some cases, kernel sources need to be modified in order to add certain functionality to the OS. Even if others provide additional functionality to kernels on GitHub, users need to compile these changes and install a new kernel version. This section provides all the required principals: kernel sources are downloaded from GitHub and then configured and compiled. Finally, the new kernel will be installed. In Chapter 4, An Arcade Cabinet, we will add some additional functionality to the LeMaker's LeMedia kernel, which is required in order to run Video Disk Recorder (VDR) smoothly.

All Allwinner A20 kernels (such as the ones used for Banana Pro) are based on kernel version 3.4.x. The subversion x is 106 at the time of writing this book. Initial kernel versions, such as...

In this chapter, we learned how to remote connect to Banana Pro in order to program an embedded board. Different kinds of IDEs have been introduced to you. In most cases, a terminal and vi editor will do the job. You have now learned the basics of shell programming, C/C++, Python, and Scratch.

Examples have been provided dealing with Banana Pro onboard LEDs and GPIOs. Last but not least, you have also learned how to compile, install, and booted your own kernel.

The next chapter deals with wire projects. You will learn how Banana Pro can be used as a hotspot, or provide an AirPlay server for wireless audio transmission. Moreover, we will take a look at databases that host web pages.