UNIX操作系统教学课件英文版章.ppt

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 3.3.4 Using the Electronic Manual: The man Command ? 1 UNIX does not leave novices or forgetful experienced users in the cold! The learn and help commands are two programs that provide assistance for using the UNIX operating system. These programs are designed to be user friendly and are intended to be used by novices, without assistance. However, these commands vary from one system to an- other, and they may or may not be installed on your system. The man (manual) command shows pages from the online system documentation. To get information about a command, type man followed by the name of the command. As you begin to learn new commands, you may want to use man to get the details about the commands. For example, to find more information about the cal command, type man cal and then press [Return]. Be patient: Sometimes the system takes a while to find the information about the selected command. The UNIX users manual is organized into sections, and the number in parentheses after the command name refers to the section number in the manual that contains the description. For example CAL(l) refers to section 1, in the User Command section. The other sections include System Administration Commands and Games, for example. 3.4 Correcting Typing Mistakes ? 1 Even the most talented typists make mistakes or change their minds when typing commands. The shell program interprets the command line after you press [Return]. As long as you have not ended your command line (by pressing [Return]), you have the opportunity to correct your typing mistakes or to cancel the whole command line. If you mistype a command name and end the command line by pressing [Return], UNIX displays a generic error message. It responds with the same error message if you type a command that is not installed on your system.The date command is mistyped. $ daye Daye: not found $ 3.