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CHAPTER 1 Before You Begin

What is UNIX?

UNIX(1) is a multi-user, multi-tasking operating system originally from AT&T that runs on a wide variety of computer systems from micros to mainframes. UNIX is made up of the kernel, the heart of the operating system; the file system, a hierarchical directory method for organizing files on the disk; and the shell, the user interface through which you command the system.

The table below shows typical commands with their VM, Microsoft DOS, and VMS counterparts.

TABLE 1. Typical UNIX Commands and VM, DOS, VMS Counterparts 
Command           UNIX  VM          DOS     VMS               
List directory    ls    listfile    dir     directory         
Copy a file       cp    copyfile    copy    copy              
Delete a file     rm    erase       del     delete            
Rename a file     mv    rename      rename  rename            
Display a file    cat   type        type    type              
Print a file      lpr   print       print   print             
Check disk space  df    query disk  chkdsk  show device/full  
Various UNIX systems also have graphical user interfaces (GUI) that provide a graphical, point-and-click interface to many of the above operations. Many vendors are now standardizing on the Common Desktop Environment (CDE) for that user interface.


With its programming tools, application programs, and networking facilities, UNIX provides a powerful, versatile computing environment. Use of UNIX is widespread, and variations of the UNIX operating system are available on most types of hardware today, including mainframes, workstations, PCs, and embedded processors.

About This Document

UNIX at SLAC: Getting Started explains necessary UNIX concepts to help you learn to use basic UNIX commands, to run a few useful programs, and to manipulate files effectively. SLAC operates UNIX workstations on the IBM and Sun platforms. Information in this document applies to all of these computers. Graphical user interfaces may make it unnecessary to know UNIX commands for most tasks; you should refer to your system documentation if you are using a vendor GUI.

The first section of UNIX at SLAC: Getting Started takes you through an initial UNIX session. You will learn how to log in, enter simple commands, and log out. Subsequent sections describe the UNIX procedures most often used:

Throughout this document, sample sessions show what you will see during work sessions on the screen of your terminal, microcomputer, or workstation. The sample screen includes prompts and commands. The UNIX system uses a prompt to tell you it is ready to accept your next command. Often this prompt is your userid and the name of the computer followed by $; the prompt shown in the sample sessions here is just $.

Commands that you type are shown in a boldface monospaced font; what UNIX displays on the screen is shown in a regular monospaced font. Thus, in the following sample session, you would type date only. Text on the right side of the page is additional comments or more detailed instructions to help clarify the example. In this sample session, the text explains that you must press the RETURN key after typing date.

If what appears on the screen during a sample session is lengthy, it may be abbreviated within angle brackets to conserve space, e.g., <system messages>.

$ date                 After you type date, press the Return key.    
Mon Nov 18 13:45:38 PST 1996                                         


The Web page at UNIX at SLAC has additional information about the UNIX system at SLAC, sources of assistance, and links to further information. If you have questions about UNIX not answered in this guide or in the UNIX at SLAC Web page, contact the SCS Help Desk, 415-926-HELP (4357).


UNIX is a registered trademark of X/Open Company, Ltd.
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