OPERATING SYSTEM BASICS:3

NAVIGATING FROM THE COMMAND LINE

Computer technicians are regularly required to perform test at the command line-level because the system is broken and cannot be taxed to support convenient graphical displays. Therefore, you must understand how Microsoft organizes disks so that you can navigate through their systems to find the required information and
tools during the troubleshooting process.
The organizational structure of a computer’s logical disks or partitions is typically described as a common office file cabinet, similar to the one depicted in the following figure.
Think of the drives in a computer as the filing cabinet structure. For example, there are three drawers that can be opened. Think of these drawers as disk drives labeled A, B, and C/D. Inside each drawer, there are hanging folders that can hold different types of items. Think of these as directories.

Microsoft Disk Organizational Structure

The hanging folders may contain different types of items or other individual folders. Think of these individual folders as subdirectories. For organizational purposes, each hanging folder and each individual folder must have a unique label on them. Items are stored inside each hanging folder or individual folder. In a real filing
cabinet, the items in folders are usually documents of different types. Pictures, tapes, and other items related to folders can also be stored in them.

Think of the items inside folders as files. Disk-based systems manage data blocks by giving them file names. Recall that a file is simply a block of logically related data, given a single name, and treated as a single unit. Like the content of folders, files can be programs, documents, drawings, illustrations, or sound files.

In order to find an item in the cabinet, you simply need to know which drawer, hanging folder, and folder it is located. This concept can be translated directly to the computer system. To locate a particular file, you simply need to know which drive, directory, and subdirectory it is located. In MS-DOS, the path to any file in the
system can be written as a direction to the computer so that it will know where the file is that it is being directed. This format for specifying a path is as follows:
C:\directory name\subdirectory_name\filename
Where C: specifies the C disk drive. The directory, subdirectory, and filenames are replaced by their names. The back slash (\) after each item indicates the presence of a directory or a subdirectory. The first slash indicates a special directory, called the root directory, which is present on all logical disks.


If the direction is to a file, the filename is always placed at the end of the path. MS-DOS allows for basic filenames of up to eight characters. It also provides for an extension of up to three characters. The extension is separated from the main portion of the filename by a period and is normally used to identify the type of the
file.

The operating system is responsible for providing the system’s user interface. The main user interface for DOS is the command line. The command line is the space immediately following the DOS prompt on the screen. All DOS commands are typed in his space. They are executed by pressing the ENTER key on the keyboard.

Microsoft Command Line

Hint: Filename extensions are not actually required for most files. However, they become helpful in sorting the files in a congested system. You should note that the operating system reserves some three-letter combinations, such as .COM and .SYS, for its own use. More information about filenames and
extensions is presented in the subsequent section about file-level commands.

In the next lesson we will learn more about different commands available on microsoft platform and how to use some of them.
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