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UNIX & file system

UNIX & file system. cosc513 Deyong Xu ID:103816 Nov.9 2000. What is Unix. A computer operating system that works with users to run programs, manages resources,and communicates with other computer system. Unix Characters. Multitasking Multiuser Multichoice Portability.

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UNIX & file system

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  1. UNIX & file system cosc513 Deyong Xu ID:103816 Nov.9 2000

  2. What is Unix A computer operating system that works with users to run programs, manages resources,and communicates with other computer system.

  3. Unix Characters • Multitasking • Multiuser • Multichoice • Portability

  4. Multitasking • Users can run several programs at the same time , such as editing a file while their another program is running on the backstage . • Users don’t have to wait for one application to end before starting another one.

  5. Multiusers • Multiple users can log on unix system at the same time. • Unix can take the commands of a number of users to run program, access file, and print documents at the same time which means a number of users can share computer resources simultaneously with each user running a different program .

  6. Multichoice • Unix has three different types of shell. • Shell is to act as an interpreter between the user and the computer. • Bourne Shell. • C Shell . • Korn Sell.

  7. Portability • Unix can be moved from one brand of computer to another with a minimum of code change • Unix can be upgraded without having all the customer’s data inputted again • Decrease the user’s learning time when moving from one system to an other . • Provide more choices among the hardware vendors

  8. UNIX File System 3 types of unix files • Regular files • Programs and data files • eg: • Source code of a program • Email received from friend • Executable programs and applications

  9. Continue … • Directory files • Basic management tools in UNIX file system • Files that contain other files • Save information of files (like size,location etc.)

  10. Continue … • Device files • Each hardware is treated like a file • Eg1 : Terminals,Printers, Keyboards, etc • Eg2:Read from a keyboard device file(input). • Eg3:Copy the file to the printer device file(print).

  11. File System Architecture • A bottom-up tree with root on the top • Root (/), a special directory file

  12. Root (/) bin/ dev/ etc/ usr/ ... Xdy/ wjj/ lgx/ A Example

  13. 3 Classes of Users • Owner: used by user • Group : shared by group members • Other : shared by any user

  14. File Three Permissions • Read permission: read 1/0 • Write permission: modify, delete 1/0 • Execute permission: run 1/0

  15. Example: permission of the file is (111 101 000)

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