Learning Debian GNU/Linux

Working with the Linux Command Prompt

To make Linux commands easy to use, they share a simple, common structure. This section describes their common structure and explains how you can obtain helpful information on the commands available to you.

Command Structure

Linux commands share the common form:

               command option(s) argument(s)

The command identifies the command you want Linux to execute. The name of a Linux command almost always consists of lowercase letters and digits. Remember that, unlike Microsoft Windows, Linux is case sensitive; be sure to type each character of a command in the proper case.

Most commands let you specify options or arguments. However, in any given case, you may not need to do so. For example, typing the w command without options and arguments causes Linux to display a list of current users.

Options modify the way that a command works. Most options consist of a single letter, prefixed by a dash. Often, you can specify more than one option; when you do so, you separate each option with a space or tab. For example, the –h option of the w command causes the output of the command to omit the header lines that give the time and the names of the fields. Typing:

root@desktop:/root# w -h

prints a list of users without the header lines.

Arguments specify filenames or other targets that direct the action of the command. For example, the w command lets you specify a userid as an argument, which causes the command to list only logins that pertain to the specified ...