To configure all your shells to work in a particular way, edit the files .bash_profile and .bashrc in your home directory. These files execute each time you log in (~/.bash_profile) or open a shell (~/.bashrc). They can set variables and aliases, run programs, print your horoscope, or whatever you like.
These two files are examples of shell scripts: executable files that contain shell commands. We’ll cover this feature in more detail in Programming with Shell Scripts.
This concludes our basic overview of Linux and the shell. Now we turn to Linux commands, listing and describing the most useful commands for working with files, processes, users, networking, multimedia, and more.