s'. The most widely used are: System V (distributed by the original developers, AT&T) AIX (IBM) Berkeley BSD (from the University of California, Berkeley) SunOS, now known as Solaris (from the makers of Sun workstations) Xenix (a PC version of Unix). The Unix operating system consists basically of the kernel and the shell. The kernel is the part carries out basic operating system functions such as accessing files, allocating memory and handling communications. A shell provides the user interface to the kernel. A number of shells are available on the Unix operating system including the Bourne shell and the C shell. The shell is basically an extensive program that runs all the time that you are logged on to the computer, and provides an interactive interface between the user and the computer functions. The C shell is the default shell for interactive work on many Unix systems.Most users don't see much difference among the variants of Unix (ULTRIX, AIX, etc.), because the shell program handles interactions between the user and the operating system. When you type a command "at Unix," you are actually typing it at the shell. The shells are the same no matter what type of Unix you use; for example, Korn shell will look the same whether the computer you use is AIX or ULTRIX. You can choose from several shells: Korn shell (ksh), C- shell (csh), TC-shell (tcsh), or Bourne-again shell (bash). Except for syntax differences, beginners won't notice many differences among the shell programs. The default shell on most shared UCS Unix computers is ksh.A number of shells are available for Unix systems, including: Bourne shell C shell Korn shell Graphical User Interface (GUI) shells The Bourne shell, which was developed by Steve Bourne at Bell Laboratories, is one of the oldest shells and, as such, has gained a lot of popularity. It is widely used for shell programming because of its efficiency and because it is available on all Unix systems. The C shell...
