Saturday, March 8, 2014

Unix Commands

Unix is a computer operating system. An operating system is the software that provides the interface between the hardware of a computer system and the applications programs that are used on it. Simply put, the operating system provides the link between the hardware of the computer and the user. Popular operating systems include DOS (used on PCs) and VM/CMS (used on mainframes, now becoming rare). Unix is available on a wide variety of computer systems, including personal computers, workstations, mainframes and supercomputers. It was developed for, and is particularly well-suited to, multi-user systems, but is now also run on 'stand-alone' machines.

Unix was first developed in the early 1970s at Bell Laboratories in the USA. It was originally developed as a system to be used by the staff in the laboratories, and it was principally intended to provide an operating system that people would enjoy using. It was designed for users who were largely computer scientists, which may explain some of the more arcane and apparently unfriendly features of Unix, such as the obscure sounding command names. AT&T (the owners of Bell Laboratories) made Unix available at nominal cost to academic users, with whom it became popular. This helped to create a market for Unix, at a time when technological changes had themselves created a need for a portable multi-user operating system. As a result Unix began to be adopted by non-academic users in the 1980's as it became commercially available. Several standards are now being worked out, and Unix is steadily becoming the standard operating system in many environments.

time line of the different UNIX systems: HP-UX, AIX, BSD, IRIX, Mac OS X, ...
(Image Source)

Some Common Commands

Following are the link for Unix Commands




MS DOS Internal & External Commands

DOS Commands are instructions to perform tasks on files and directories. They are case insensitive. And as you already know, file is the area where we store group of information or data, and collection of group of files is called a directory.  

The internal commands reside in COMMAND.COM, which loads into memory when the computer system is started; these commands do not reside on disk. The external commands are files that do reside on disk and have an extension of .COM, .EXE, or .BAT. Both command types are executed from the MS-DOS prompt.


For Detailed Internal and External Commands with Examples.
Kindly refer the following link 




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