Getting Started

Login

When you log in on a system, a program called login determines whether your user name and password are correct by checking the file /etc/passwd. The /etc/passwd file is a special system file that contains a listing of all the valid users and encrypted versions of their passwords on a system. See your System Administrator for more details, or passwd(4).

Once you type the correct user name and password, the login program starts (spawns) a shell (the POSIX Shell (/bin/posix/sh) is the default shell on newly delivered systems) so you can begin executing system commands. HP-UX supports three other shells: Bourne Shell (/bin/sh), Korn Shell (/bin/ksh), and C Shell (/bin/csh).

Command Line

When the shell is ready for your next command, it displays a prompt on the terminal display screen. Commands are given to the shell by typing the command name followed by options and/or parameters (called command arguments) as appropriate for that command, and pressing the Return key. The default POSIX Shell, Korn Shell, and Bourne Shell prompt is a dollar sign ($). The default C Shell prompt is %. Once you have typed a command line, the shell interprets and executes it. For example:

$ echo Welcome to Korn Shell
Welcome to Korn Shell
$

This example shows the echo command followed by its argument, a string of text that is to be displayed on (echoed to) the terminal. Output from the echo command appears on the next line: Welcome to Korn Shell. (Note that echo is a shell built-in and so no process is spawned. However, /bin/echo is a utility and will spawn a process and assign it a process ID (process identifier).

The software for each shell is shipped with HP-UX and resides on your HP-UX file system:

The rest of this tutorial deals mainly with the POSIX and Korn Shells. If you do not understand the login process or the file directory system, or if you have questions about shell structure or interaction with the shell, read about these topics in Using HP-UX.