CS 1451 UNIX OPERATING SYSTEM Lecture 1

CS 1452 OVERVIEW UNIX Operating System  Multi-Tasking  Multi-User  Interactive Supports computer systems  Standalone  Networked

CS 1453 HISTORY Created by Computer Science Research Group at Bell Labs Circa 1970 Objectives of the creators “... to create a computing environment where they themselves (the staff of CSRG) could comfortably and effectively pursue their own work - programming research.”

CS 1454 MULTI-TASKING The ability to perform several tasks -- processes -- at the same time Allows background/foreground processing

CS 1455 MULTI-USER More than one person may use the system at the same time User doing more than one thing at the same time Relatively secure environment for multiple users Multiple protection levels for files, processes

CS 1456 INTERACTIVE User issues commands System performs commands System reports results User issues more commands

CS 1457 Working in the CTU Lab Logging in and out Working with the terminal emulator

CS 1458 Handout: terminal emulator See separate handout for how to use TerraTerm Pro terminal emulator Emulator simulates a dumb terminal accessing UNIX Handout shows how start, configure emulator Use Windows services for printing – not UNIX print services

CS 1459 Login Name Login names Must be at least 6 characters long Only the first 8 characters are significant Case sensitive (as is most of UNIX) Spaces allowed, not recommended Control characters and punctuation are permitted  Most people avoid them  Control-s and control-g are not permitted

CS Login continued Best login names contain characters, mixed case, digits Login must exist on the system prior to logging in as that user Login names must be unique Only system admin (Super-User) may issue logon IDs Login entry followed by “Return”

CS Login Names Valid Entries Invalid Entries cowboy the_black_marauder(> 8 char) marauder john smith(contains a space) johnny sarah^g(contains control-g) johnnyQ sam(too short) cee3po MyLoGiN it’s_me

CS Passwords Must be at least 6 characters long Only the first eight characters are significant Case sensitive Spaces, punctuation, and control characters are permitted (but not control-s and control-g) Must be different than login name Must differ from the old password

CS Passwords Any user may change their own password Super-User (i.e., systems administrator) cannot decode your password Must be issued a new password if old one forgotten Passwords never appear on the screen

CS passwd command $ passwd system prompts for old password system then prompts for new password system then prompts for new again if change occurs no message appears = UNIX Principle: No news is good news

CS Login Failure A login failure will generate a login error which must be acknowledged If login does not exist Screen will be cleared and a new login screen generated If login does exist, but password is incorrect Only the password entry is cleared The cursor is positioned for a new password attempt. After a certain number of tries, screen is cleared or system quits talking to you

CS Login Failure (cont) Frequently a login will look correct, but is not It may contain a leading space or tab which are difficult to see If login continues to fail after several tries … Contact instructor, then system administrator.

CS Successful login See the $ prompt – you’re in System ready to accept commands

CS Minimizing, enlarging windows Use the Windows screen size controls to maximize, minimize windows DO NOT change window size during a vi editing session You can toggle from the UNIX terminal session to other Windows tools, like Word You can run multiple TerraTerm windows and sessions simultaneously