MS DOS Command: UNFORMAT.COM

Reference from Microsoft MS-DOS cmd help

Description

Restores a disk that was erased by using the FORMAT command.

UNFORMAT restores only local hard disk drives and floppy disk drives; it cannot be used on network drives. The UNFORMAT command can also rebuild a corrupted disk partition table on a hard disk drive.

Syntax

UNFORMAT drive: [/L] [/TEST] [/P]

Parameters

drive:

Specifies the drive that contains the disk on which you want to recover files.

Switches

/L	Lists every file and subdirectory found by UNFORMAT. If you do not specify this switch, UNFORMAT lists only subdirectories and files that are fragmented. To suspend scrolling of the displayed list, press CTRL+S; to resume scrolling, press any key.
/TEST	Shows how UNFORMAT would recreate the information on the disk, but does not actually unformat the disk.
/P	Sends output messages to the printer connected to LPT1.

Related Command

For information about formatting a disk, see the FORMAT command.

Remarks

Limitation on the UNFORMAT command

If the FORMAT command was used with the /U switch, UNFORMAT cannot restore the disk to its previous condition.

Unformatting a disk

The UNFORMAT command can restore your disk by using information in the root directory and file allocation table on the disk.

As UNFORMAT rebuilds the disk, it displays how many subdirectories it has found; if you specified the /L switch, it also shows you all files in each subdirectory.

If UNFORMAT finds a file that appears to be fragmented (that is, stored in separate places on the disk), it cannot recover the file because it cannot locate the remaining portions of the file. In this case, the UNFORMAT command prompts you to confirm whether you want UNFORMAT to truncate the file (that is, recover only the first part of the file that it can locate) or delete the file altogether.

If UNFORMAT does not prompt you for a specific file, that file is most likely intact. In certain circumstances, however, UNFORMAT may not recognize that a file is fragmented, even though it has located only a portion of the file. If this happens to a program file, the program does not run properly. If this happens to a data file, information is lost and the program that created the data file may not be able to read it. In these cases, your only recourse is to restore the files from your original floppy disks or backup files.

Sector size of the hard disk

The sectors on your hard disk must be 512, 1024, or 2048 bytes.

Examples

To determine whether UNFORMAT can restore a formatted disk in drive A, type the following command:

unformat a: /test

To restore a formatted disk in drive A, listing all files and subdirectories, type the following command:

unformat a: /l