MS DOS Command: DEFRAG.EXE

Reference from Microsoft MS-DOS cmd help

Description

Reorganizes the files on a disk to optimize disk performance. Do not use this command when Windows is running.

Syntax

DEFRAG [drive:] [/F] [/S[:]order] [/B] [/SKIPHIGH] [/LCD | /BW | /G0] [/H] DEFRAG [drive:] [/U] [/B] [/SKIPHIGH] [/LCD | /BW | /G0] [/H]

Parameters

drive:	Specifies the drive that contains the disk you want to optimize.
/F	Defragments files and ensures that the disk contains no empty spaces between files.
/U	Defragments files and leaves empty spaces, if any, between files.
/S	Controls how the files are sorted in their directories. If you omit this switch, DEFRAG uses the current order on the disk. The colon (:) is optional. The following list describes each of the values you can use to sort files. Use any combination of the values, and do not separate these values with spaces. N In alphabetic order by name N- In reverse alphabetic order by name (Z through A) E In alphabetic order by extension E- In reverse alphabetic order by extension (Z through A) D By date and time, earliest first D- By date and time, latest first S By size, smallest first S- By size, largest first
/B	Restarts your computer after files have been reorganized.
/SKIPHIGH	Loads DEFRAG into conventional memory. By default, DEFRAG is loaded into upper memory, if upper memory is available.
/LCD	Starts DEFRAG using an LCD color scheme.
/BW	Starts DEFRAG using a black and white color scheme.
/G0	Disables the graphic mouse and graphic character set.
/H	Moves hidden files.

Remarks

Network and INTERLNK drives

You cannot use DEFRAG to optimize network drives or drives created with INTERLNK.

Disk information reported by DEFRAG and CHKDSK

Disk information that DEFRAG reports differs from information that CHKDSK reports. DEFRAG reports hidden and user files as one number; CHKDSK reports numbers for each type. DEFRAG counts the root as a directory; CHKDSK does not. DEFRAG does not count the volume label as a file; CHKDSK does.

Start DEFRAG only from MS-DOS

If you start DEFRAG from a program such as Microsoft Windows, you may lose data.

DEFRAG exit codes

The following list briefly describes the meaning of each DEFRAG exit code (ERRORLEVEL parameter):

0	The defragmentation was successful.
1	An internal error occurred.
2	The disk contained no free clusters. To operate, DEFRAG needs 1 free cluster.
3	The user pressed CTRL+C to stop the process.
4	A general error occurred.
5	DEFRAG encountered an error while reading a cluster.
6	DEFRAG encountered an error while writing a cluster.
7	An allocation error occurred. To correct the error, use the SCANDISK command.
8	A memory error occurred.
9	There was insufficient memory to defragment the disk.

You can use the ERRORLEVEL parameter on the IF command line in a batch program to process exit codes returned by DEFRAG. For an example of a batch program that processes exit codes, see the CHOICE command.

Examples

To load DEFRAG into conventional memory and specify that DEFRAG sort files according to the date they were created, from latest created to earliest created, type the following command:

defrag c: /f /sd- /skiphigh

This example fully optimizes drive C, but slows DEFRAG.