Redirection > >> < | redirect input output append pipe in MS DOS command, A number of DOS commands send output to the screen and/or require input from the user. Redirection is a mechanism whereby the output of a command can be fed either to some other device for example, a printer or file, or to another program or command

Redirection

A number of DOS commands send output to the screen and/or require input from the user. Redirection is a mechanism whereby the output of a command can be fed either to some other device for example, a printer or file, or to another program or command.

There are four redirection functions:

>

Redirects a command's output from the "standard output device" (usually the monitor) to another device (e.g. printer) or a file.

Syntax:

To redirect output to a device:

Command > Device

To redirect output to a file:

Command > Filename

Acceptable Device names are, CON (Monitor), PRN (LPT1 - assumed to be the printer), LPT1 - 3 (Parallel Ports - usually connected to a printer), COM 1 - 4 (Serial Ports) and NUL (an electronic void).

If anything other than a recognized device is specified, it is assumed to be the name of a file. If a file already exists with the specified Filename, it is overwritten without any Warnings. Let us see some Examples to better understand it.

Probably the most common uses of this redirection function is to send directory listings to the printer or to save them as a file. To print out a sorted directory listing of all files in the Windows directory:

DIR c:\windows /o/a > PRN

To create a file containing the directory listing of the same directory:

DIR c:\windows /o/a > d:\windows.txt

>>

Appends the output from a command to the specified file.

Syntax:

Command >> Filename

If Filename does not exist, it is created. If Filename does exist, the output from the command is added to it, unlike the > function where the original contents are overwritten. Let us better understand it with example.

To add the directory listing of the files in the c:\windows\system directory to that created before:

DIR c:\windows\system /o/a >> d:\windows.txt

Sample Chapters from book DATA RECOVERY WITH AND WITHOUT PROGRAMMING by Author Tarun Tyagi

Publishers of the Book Number of Pages ISBN Price of the Book BPB Publications, New Delhi, India 540 81-7656-922-4 $69.00 (Including Shipping Charges, Cost of Book and Other expenses, Free Source Code CD included with the Book)

page 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15