Programs for the root filesystem
Now, it is time to start populating the root filesystem with the essential programs and the supporting libraries, configuration, and data files that it needs to operate, beginning with an overview of the types of program you will need.
The init program
You have seen in the previous chapter that init is the first program to be run and so has PID 1. It runs as the root user and so has maximum access to system resources. Usually, it runs shell scripts which start daemons: a daemon is a program that runs in the background with no connection to a terminal, in other places it would be called a server program.
Shell
We need a shell to run scripts and to give us a command-line prompt so that we can interact with the system. An interactive shell is probably not necessary in a production device, but it is useful for development, debugging, and maintenance. There are various shells in common use in embedded systems:
bash: is the big beast that we all know and love from desktop...
