CS 497C - Introduction to UNIX
Lecture 2: Work with Files and Directories
Chin-Chih Chang chang@cs.twsu.edu

Working with Files and Directories
* Many commands refers to files and directories. 
* mkdir - creating a directory
$ mkdir docs
* ls - listing files and directories
$ ls
docs
* pwd - show your current directory

Working with Files and Directories
$ pwd
/home/romeo
cd - change directory
$ cd docs
$ pwd
/home/remeo/docs
* echo - write its arguments to standard output
$ echo This is the first message > note1
$ echo This is the second message > note2

Working with Files and Directories
$ ls
note1       note2
* cat - concatenate and display files
$ cat note1
This is the first message.
* wc: couting lines, words and characters
$ wc note1
       1           5           26 notel
$ wc -l note1
          1 note1

Working with Files and Directories
* ls -l - checking the file attributes
$ ls -l
total 2
-rw-r--r--   1 romeo    staff      26 Aug 22 02:05 note1
-rw-r--r--   1 romeo    staff      27 Aug 22 02:06  note2
* man - find and display reference manual pages
$ man ls

How It All Clicked
* Till UNIX came on scene, operating systems were designed with a particular
  machine in mind. Programs designed for one system simply wouldn't run on 
  another.
* Ken Thompson and Dennis Ritchie designed and built a small system having 
  an elegant file system, a command interpreter (the shell) and a set of 
  utilities.
* In 1973, they rewrote the entire system in C.

How It All Clicked
* UC Berkeley created BSD UNIX.
* The other brands of UNIX: Xenix, BSDi, BSD/OS, FreeBSD, SunOS, Solaris, 
  HP-UX, AIX, Ultrix, Digital UNIX, IRIX, SCO Open Server, SCO UnixWare.
* AT&T unify their own System V 3.2, BSD, SunOS and XENIX into System V 
  Release 4 (SVR4).

The Internet
* DARPA commissioned UCB to implement TCP/IP on BSD UNIX.
* TCP/IP is a set of protocols used by the Internet for communication.
* The incorporation of TCP/IP into UNIX and its use as the basis of 
  development were two key factors in the rapid growth of the Internet (and 
  UNIX).

The Windows Threat
* Windows - a graphical user interface (GUI) that uses the mouse rather than 
  arcane and complex command options to execute a job.
* Windows first swept the desktop market (with Windows 3.1/95/98/Me) and then 
  made significant inroads into the server market (with Windows NT/2000).
* The MIT introduced X Window - the first windowing system for UNIX.

Standards and POSIX
* In 1992, AT&T's UNIX business was sold to Novell. Novell then turned over 
  the UNIX to X/OPEN. The Open Group published the single UNIX Specification.
* The Portable Operating System Interface (POSIX) is a set of standard 
  operating interfaces based on UNIX.
* Most UNIX vendors cooperate with The Open Group and also build products 
  based on the UNIX standard.