---
name: "fdformat"
section: "1"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["linux", "openbsd"]
url: "https://new.carta.tech/fdformat"
---

# fdformat(1)

format floppy disks

## NAME

**fdformat** – format floppy disks

## SYNOPSIS

**fdformat** \[**-nqv**\] \[**-c** *cyls*\] \[**-F** *fillbyte*\] \[**-g** *gap3len*\] \[**-h** *heads*\] \[**-i** *intleave*\] \[**-r** *rate*\] \[**-S** *secshft*\] \[**-s** *secs*\] \[**-t** *steps\_per\_track*\] *device\_name*

## DESCRIPTION

**fdformat** formats a floppy disk at device *device\_name*. *device\_name* should be a character device; it may be given either with a full path name of a raw device node for a floppy disk drive (e.g., */dev/rfd0c*), or default name in an abbreviated form, (e.g., *fd0*). Note that any geometry constraints of the device node (minor device number) are meaningless, since they're overridden by **fdformat**.

The options are as follows:

- **-c** *cyls*

  Number of cylinders (40 or 80).

- **-F** *fillbyte*

  Use *fillbyte* as fill byte.

- **-g** *gap3len*

  Length of gap at the end of any sector (“gap 3”).

- **-h** *heads*

  Number of floppy heads (1 or 2).

- **-i** *intleave*

  Sector interleave to be used.

- **-n**

  Don't verify floppy after formatting.

- **-q**

  Suppress any normal output from the command, and don't ask the user for confirmation whether to format the floppy disk at *device\_name*.

- **-r** *rate*

  Data transfer rate in kilobyte/sec (250, 300, or 500).

- **-S** *secshft*

  Sector size code: 0 for 128, 1 for 256, and 2 for 512 byte sectors.

- **-s** *secs*

  Number of sectors per track (9, 10, 15, or 18).

- **-t** *steps\_per\_track*

  Number of steps per track. An alternate method to specify the geometry data to write to the floppy disk.

- **-v**

  Don't format; verify only.

If the **-q** flag has not been specified, the user is asked for confirmation of the intended formatting process. In order to continue, an answer of “y” must be given.

## EXIT STATUS

An exit status of 0 is returned upon successful operation. Exit status 1 is returned on any errors during floppy formatting, and an exit status of 2 reflects invalid arguments given to the program (along with appropriate information written to diagnostic output).

## DIAGNOSTICS

Unless **-q** has been specified, a single letter is printed to standard output to inform the user about the progress of work. First, an “F” is printed when the track(s) is being formatted, then a “V” while it's being verified, and if an error has been detected, it will finally change to “E”.

## SEE ALSO

[fdc(4)](/fdc/4.md)

## HISTORY

**fdformat** was developed for 386BSD 0.1 and upgraded to the new [fdc(4)](/fdc/4.md) floppy disk driver. It later became part of FreeBSD 1.1, and was then ported to OpenBSD 1.2.

## AUTHORS

The program was contributed by Joerg Wunsch, Dresden, with changes by Serge Vakulenko and Andrew A. Chernov, Moscow.