Introduction to Web Design and Computer Principles

CSCI-UA.0004-002

Mehan Jayasuriya

Week 2, 9/8/15

Today's Agenda:

  • What is an operating system?
  • What is UNIX?
  • Using the terminal
  • SSH
  • NYU i6
  • Basic UNIX commands
  • UNIX permissions

What is an operating system?

Operating systems you might use

What does the OS do?

A lot of things have operating systems

UNIX is one of the oldest operating systems

You might be using UNIX right now

Let's fire up the terminal and use some basic UNIX commands

Unix commands

  • cd: change directory
  • ls: list
  • mkdir: make directory
  • cp: copy
  • pwd: see current directory
  • rm: remove
  • chmod: change permissions

What is SSH?

What is NYU's i6 server?

Let's log into our i6 account

What we just did


	ssh netID@i6.cims.nyu.edu
	[enter password]
	ls
	cd [directory]
	logout
				

UNIX permissions

Types of permissions

  • r: read
  • w: write
  • x: execute
  • -: no access

Types of users

  • u: user (i.e. you)
  • g: group (i.e. our class)
  • o: other (i.e. the world)

Converting permissions to decimals

Putting it all together

Wow that was really confusing

Permissions you'll use most often:

  • 755: you have all rights, group and world can only read and execute (standard for directories)
  • 644: you can read and write, everyone else can only read (standard for files)
  • 777: everyone has all rights
  • 700: you have all rights, everyone else has none