Software:recover (command)

recover

Original author(s)	Chris Peters
Developer(s)	Microsoft, IBM, Digital Research, Novell, Imre Leber
Initial release	1983, 40–41 years ago
Written in	MS-DOS: x86 assembly language
Operating system	MS-DOS, PC DOS, SISNE plus, OS/2, eComStation, ArcaOS, Windows, DR DOS, FreeDOS
Platform	Cross-platform
Type	Command
License	MS-DOS: MIT FreeDOS: GPL
Website	docs.microsoft.com/en-us/windows-server/administration/windows-commands/recover

In computing, recover is a primitive file system error recovery utility included in MS-DOS / IBM PC DOS versions prior to DOS 6.0 and a number of other operating systems.

Overview

Typing recover at the DOS command-line invoked the program file RECOVER.COM or RECOVER.EXE (depending on the DOS version). recover proceeded under the assumption that all directory information included on a disk or disk partition was hopelessly corrupted, but that the FAT and non-directory areas might still contain useful information (though there might be additional bad disk sectors not recorded in the FAT).

The program removed all subdirectories and all entries in the root directory, and then created new files with names such as "FILE0001.REC" in the root directory, corresponding to the valid allocation chains that were found in the FAT area (excluding disk clusters that were tested and found to have hardware errors). A formerly bootable disk would no longer be bootable after recover had executed. The range of circumstances in which recover was genuinely useful was quite limited, and well-meaning DOS users sometimes created havoc by running recover under the misconception that it was a file undelete utility.

In DOS version 5, another mode of operation was added: specifying a single filename on the command line would cause the program to test all the disk sectors used to store the file, and shorten the file by omitting sectors which tested bad.

DR DOS 6.0 includes an implementation of the recover command. The command is also available on SISNE plus and IBM OS/2. The FreeDOS version was developed by Imre Leber and is licensed under the GPL.

See also

• Chkdsk
• Scandisk
• Norton Utilities
• List of DOS commands

Further reading

• Special Edition Using MS-DOS 6.22, Third Edition. Que Publishing. 2001. ISBN 978-0789725738. 
• Kathy Ivens; Brian Proffit (1993). OS/2 Inside & Out. Osborne McGraw-Hill. ISBN 978-0078818714. 
• John Paul Mueller (2007). Windows Administration at the Command Line for Windows Vista, Windows 2003, Windows XP, and Windows 2000. John Wiley & Sons. ISBN 978-0470165799. 

External links

• recover | Microsoft Docs
• Open source RECOVER implementation that comes with MS-DOS v2.0