Information Organization and File Management
What is Information?
For our purpose, we refer to a set of instruction i.e program and data as information. A program is a sequence of instructions to be executed by a computer. Data is what a program operates up on. The program and the data are stored in computer memory before a program is executed. Information is stored in auxiliary memory of a computer in the form of files.
File:
In computer terminology, a file is an organized collection of data / information stored on a storage device such as floppy Hard Disk or magnetic type. A computer file is not very different form a conventional paper file. However, usually one computer file is used to store only one type of information. Different types of files are used in computers.
Naming of Files:
The files, containing information, should have proper names to identity for later use.
Rules for Naming Files:
1. The file name should contain only letters of alphabet (Character) and some special character.
2. The name should not be longer than 8 characters.
3. Extension of file is optional with a maximum of 3 characters.
4. The file name and the extension should be separated by a period. i.e
Example:
Letter, txt, ref-refcrs.not, etc.
Note:
The files should not be named arbitrarily. It is advisable to have so meaningful name so that it represents the contents inside the file.
The following extension are specifically used:
Com/exe: Command or executable file.
BAT: Batch files
BAK: Backup files of some other files.
Directory:
A directory is special type of file that contains other files. It is also called as folder. A group of files can be stored in a directory.
The relation between files, directories and disk is similar to the relation between papers (Documents), filling folders and filling cabinets. Just as a folder may contain papers (Documents) and other folders, a directory may also contain directories within it. Such diratory within a dir is called subdirectory.
Storing group of related files in different directories makes it easy to find a file. For example, all the files that come with MS- DOS’s software are stored in a single directory that is usually named DOS. If one ever needs to locate an MSDOS file, one knows where to look. Like files, directories can also be created. For example, to store all the files containing information about admission, a directory called ADM can be created to store these so that is easier to find them. A directory can also be created within a directory, which is called as a subdirectory. Strictly speaking all directories are subdirectories. Except one, this is called a root directory. It is represented by / in DOS and / in UNIX.
A prompt C :> on a DOS system indicates that you are presently in the root directory of the drive C.
Drives:
Just like a directory is a group of files. A drive is a group of directories or files themselves and it is represented by a letter. It can be a floppy drive(Usually designed as A and B ) or a HDD designated as C, D…. etc.
Path:
A path is the course that leads form the root directory of a drive to the file, one wants to use.
To access the file merit.txt one must go form root directory through the ADM directory through MRT directory to the file merit.txt. To specify the same path at the command prompt, one would type it as shown below.
C:/-Drive
ADM-root Directory
MRT- Directory
Merit.txt -Subdirectory
Can
This is called path to the file merit.txt. It starts with a drive letter and is followed by folder names, separated by a blackslash(l). For various file operations, sometimes full path need to be specified.
Wild Cards:
If you want to carryout a task for a group of files whose names have something in common, you don’t have to use the same command repeatedly for each filename. You can use one or more wildcards to specify group of files. A wildcards is a character that, can represents one or more character in a filename. The wildcard ‘*’ represents one or more character that a group of files has in common, whereas ‘?’ represents a single character that group of files has in common.
The following table shows examples.
|
Wild Card |
What it represents |
|
*.txt |
all files with a .txt extension |
|
mrt* |
all files named mrt with any extension |
|
m*.* |
all files beginning with letter m regardlers of their extension |
|
???.* |
all files with 3 letter names, with any or no extension |
One can include multiple wild cards in a command.