When you type a command and press the Enter key to execute this command, it's usually interpreted by some kind of command interpreter program, known as a shell. In this book we will use this term when we refer to a command interpreter program.
If you are running your web server on some Unix flavor, it is likely that you are using the C-style shell (e.g., csh or tcsh) or the Bourne-style shell (e.g., sh, ksh, or bash) for starting programs from the command line. In most examples in this book, it doesn't matter which shell program is used. In places where a different syntax should be used for different shell programs, we will say so.
The following command-line conventions are used in this book:
panic% is a shell prompt when you are logged on as a non-root user, usually yourself.
panic# is a shell prompt when you are logged on as root. It implies that you have to become a root user to run the command. One of the ways to switch to root mode is to execute the su utility and supply the root user password.