Introduction To Unix

INTRODUCTION TO UNIX THE UNIX OPERATING SYSTEM Background UNIX had a modest beginning at AT and T Bell Laboratories during the late Sixtes. It was primarily developed to pursue “programming research”. Until UNIX came on the scene, operating systems were designed with a particular machine in mind. Similarly, computers were built for specific operating systems. They were invariably written in assembler which understood and accessed the hardware well and had good speed. In those days, hardware was expensive and human labour comparatively cheap. Later, hardware prices started coming down sharply and labour costs started shooting up. The focus shifted to improvement of the environment of the software designer. The founder of UNIX T.R.(Thompson & Ritchie) took the important decision to trade off speed against utility and portability. UNIX was developed with the idea of porting to any hardware. Originally written in assembly language, UNIX was rewritten in 1973 using the C language. CONCEPT In the Unix operating system everything is represented with a file. We mean everything like your documents floppy and hard disks monitor keyboard etc. all are represented by a file to put it simply a file is structured to store information. A process is an instance of a running program. A Process is said to be born when the program starts execution and remains alive as long as the program active. After execution is complete. The processes cease to exist and is said to die. Portability— applications in one platform can be ported to another platform easily Multi-user operation---many users can use the system at the same time Device independence----can work on a variety of hardware platforms Hierarchical file system---this is characteristic about which we will learn in detail later. Filters, redirections, pipes and tree-------various utilities, about which we learn later on. Multitasking-----we can do more than one task like rating e-mail and compiling programs at the same time Basic command for UNIX 1) LS [ directory]----list of files

2) Pwd----name of current directory 3) Jobs—lists jobs running in current shell 4)ps-ux--- last of all processes you are running 5) man command name---gives cryptic Unix when notes 6) cat find name---print the file content on screen 7)more fine name---print the content of a fine to the screen. Stopping at the bottom of each page so you can read that file. Uses space bar to continue queue to quite. 8) Head - n file name---show the first n line of a file. 9 )tail – n file name---show the last n lines of a file 10 )lpr file Name – sends a file to line printer 11)lpq ---list the print queue 12)lprm jon # --- to remove the job from the print queue 13)cp file name 1 directory/filename 2 ---copy file to adirectory. 14)mv file name 1 directory/[file name 2]---moves a file.use also for renaming 15 rm file name---deletes the file system 16)mkdir directory—to create a folder or directory. 17 rm dir directory --- remove directory. 18finger user name --- check to see if some one is logged on 19 ch mod code file name –sets protection levels, needed to make a script executable. 20history ---list the last commans used 21xterm---opens a new xprienter

Induction to dos Definition Dos stands for disk operating system .ms-dos stand for Microsoft disk operating system named after the developer of the operating system, Microsoft corporation USA Operating system An operating system is a collection of programs that manages system resources and aids in the execution of application program the operating system acts as an interface between the user and the computer DOS commands Dos commands are used to communicate with the computer dos commands are of two types, internal and external Internal commands reside in a portion of the computer’s memory as soon as dos gets loaded and are always available to the user .COMMAND.COM is one of the operating system program that gets loaded into computer memory during the machine startup and reside in the memory. there are certain dos commands stored with COMMAND.COM. These commands are referred as internal dos commands. Example Internal commands Mkdir, chdir, copy, cls, path, del. External commands are of a loaded from the disk into the memory, before they can be executed. These are the commands which exist as separate program files and reside on the disk. Example External commands Tree, xcopy, diskcopy, more, move, format etc Internal commands. Copy Syntax: copy [d:][path]<source filename >[d:][path]
Example: c:\>copy c: chapter2 c2 Type Syntax: c:\>del Example: c:\>type chap1 Erase/del Syntax: c:\>del Example:del a:c2 Path Syntax: c:\>path =[d] Example: c:\>path = c:\windows ;\foxpro; Md/mkdir Syntax: c:\>md<derectory name> Example: c:\>md test Cd/chdir Syntax: c:\>cd Example: c:\>cd test Rd/rmdir Syntax: c:\>rd Example: c:\>rd test External commands More Syntax: c:\>more Example: c:\>more test.txt Deltree Syntax: c:\>deltree Example: c:\>deltree new Move Syntax: c:\>move [source directory][target directory] Example: c:\>move c:\mydir\*.* c:\newdir Undelete Syntax c:\>undelete Example: c:\>undelete newdir