A Overview of UNIX
...the operating system, the UNIX kernel is considered to be the operating system or the core of the operating system. It is loaded at start up and manages the resources of the system. Some basic functions performed by the kernel are, it manages the memory, it schedules the work done by the CPU (central processing unit), it transfers data from one part of the machine to another, and it interprets and executes instructions from the shell and it enforces file access permissions (Unix Overview, 5). It doesn’t matter which computer is used, the user will always have the same kernel interface to work with because the hardware is “hidden” by the kernel (Sol, Web developers, 1). As mentioned in the above paragraph, the shell interprets commands. It takes each command and passes it to the operating system kernel to be acted upon. It then displays the results on your screen. The user may have multiple shells open at one time and all work is done on the shell. Some common shells are Bourne shell (sh), C shell (csh), Korn shell (ksh), TC Shell (tcsh), and Bourne Again Shell (bash) (Unix Shell, 1). One unique feature of the Unix System is the file system. The UNIX file system is a hierarchical file structure. All files in the UNIX file system are organized into a multi-leveled hierarchy called a directory tree. The picture of a family tree is an example of how the UNIX file system would be organized. The UNIX file system contains such files as Ordinary files, Directories, Special files, and Pipes (Unix File systems, 1, 2, 3). Another feature of the Unix System is the utilities. The UNIX system has several hundred utility programs which are often referred to as commands. The utilities part of UNIX accomplishes universal functions such as editing, file maintenance, printing, sorting, programming support, online information, etc. In addition, some of the single functions can be grouped together to accomplish more complex tasks (Unix Overview, 6). Some other features of the UNIX system are the editors and mail utilities. The text editor is a program which enables you to create and manipulate the text in a computer file. It is not a word processor even though the editor has some of the features of a word processor. Some common editors are vi which is the standard display editor, pico which is a simple text editor used by the mail program Pine, and emacs which many people consider the best tool for editing text in the Unix environment (Boas, Text editors, 4). The common mail utility commands are mail, mailx and pine. The standard Unix mail utility which comes with most UNIX systems is called “mail”. Another improved version is called “mailx”. Pine is one alternative to regular Unix mail. It is a screen oriented, message handling tool (Unix email, 1, 2). The two most common GUI’s (graphical user interface) are Spine and Linux. Spine is a system that supports the construction and operational use of functionally-integrated working environments in Unix networks. It provides its users with access to resources on heterogeneous computer systems linked to the network as if the resources are located on a single compute...