CS 497C – Introduction to UNIX Lecture 2: Work with Files and Directories Chin-Chih Chang

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 note 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.