Week 2File Systems & Unix Commands

File System Hierarchy

File Names & Extensions• File Name: used so that the computer can easily remember

the date within • File Extensions: allow the operating system to know what

application opens the file

File Manipulation

What is AFS?• AFS (Andrew File System): is a distributed file system which

makes it possible for users to access information from any computer on a network

• Security• Kerberos: used to authorize the user to the system• ACL (Access Control List): used to grant privileges to users for all

directories on the network.

• Volumes: To help in scalability, AFS uses volumes, a volume keeps a set of related files & directories together on a disk, which allows admins the ability to add and remove without us losing our data

AFS File Tree

Pathnames

Relative Pathnames• ~/ : The ~/ references your home directory, this will be used as

a shortcut to get us back to our home directories• .. : refers to the directory above the current working directory• . : refers to the current working directory

Relative pathname practice• The path can be expressed

../.elm/inbox~/.elm/inbox./../.elm/inbox

Client/Server Relationship• Server: Is a powerful computer dedicated to managing, which

sole task is to govern access to information and “serve” information requested by the client.

• Client: Is a normal computer, or another server, that request the information from the server and relies on information from the server to complete its task

• Who is the client and who is the server on NCSU network?

SSH• Secure Shell: is a program that allows a computer to connect

over a network and execute commands on a remote computer• It provides a secure and encrypted connection over an insecure

network• Also protects networks from attacks such as IP spoofing, IP source

routing, and DNS spoofing• Uses “tunneling” to group information together in secure SSH

packets before sending it over a network

Accessing AFS• Windows Students • Double click putty.exe icon on desktop• Click ‘Eos’ then ‘Load’

• Mac Students• Open ‘Terminal’• Enter ‘ssh –X userID@remote-linux.eos.ncsu.edu’• *replace userID with your UnityID