Backup command

Updated: 05/21/2018 by Computer Hope
backup command

The backup command enables MS-DOS users to back up the data on their computer.


Backup is an external command available for the following Microsoft operating systems. The external file was used with MS-DOS 4.0x and earlier. In the last version of MS-DOS, version 5, to support the backup command, backup.exe was used as the external file.


MS-DOS 6.0, 6.2, 6.21, and 6.22 users utilize the msbackup command. However, this file is still available to these users on the MS-DOS 6.0 and 6.22 supplemental disk.

Backup syntax

MS-DOS 2.x - 5.x syntax

BACKUP [Source:\Path\File name] [Target:] [/s] [/m] [/a] [/d:date] [/t:time] [/f:size] [/L:LogDrive:\Path\Log]
Source:\Path\File name The source, path, and file name of the location of the file that you want to backup.
Target: The target drive for the backup file.
/s Makes a backup of all files, directories, and subdirectories in the specified source location.
/m Backup all files that have changed since the last backup.
/a Adds a new backup file to existing backups instead of overwriting them.
/d:date Backup files that were created or modified since the date specified.
/t:time Backup files that were created or modified after this time.
/f:size Create backup files in a specific size so they can be saved to an external storage such as a floppy disk drive.
/L:LogDrive:\Path\Log Creates a log of the backup and specify where the log is to be saved.

Backup examples

backup c:\work\*.* d: /s

The example above would create a backup of all the files and subdirectories in the working directory and save the backup to the d: drive.