Man pages › Compared with Linux and the BSDs

`fdformat(1)` on Solnix vs Linux and the BSDs

On Solnix, fdformat is the illumos /usr/bin/fdformat, which its own page says is superseded by rmformat(1). Its flags differ from FreeBSD fdformat(8) and NetBSD fdformat(1): -f means 'force' (not a density or a device), and -v is verify-after-format (not verify-only).

The manual pages

Solnix: fdformat(1) from pkgs.solnix.illumos-world-man · illumos.org
FreeBSD: fdformat(8) 15.1-RELEASE
NetBSD: fdformat(1) 11.0

What Solnix runs

A default Solnix system runs the illumos fdformat at /usr/bin/fdformat, and no other variants are shipped. The page says rmformat(1) replaces it and provides most but not all of its functionality. The bundle has no Linux counterpart page.

Differences

Compared with	Topic	What differs
FreeBSD	`-f` meaning	Solnix `-f` forces formatting without asking for confirmation. FreeBSD `-f` fmt selects a density by kilobyte format, as described in fdcontrol(8). The same flag letter does unrelated things. Source: Solnix fdformat(1) -f; FreeBSD fdformat(8) -f fmt
NetBSD	`-f` meaning and device selection	Solnix `-f` forces formatting. NetBSD `-f` device names the device to format, defaulting to /dev/rfd0a. On Solnix the device is an optional positional devname, e.g. floppy0 or rdiskette0. Source: Solnix fdformat(1) -f, OPERANDS devname; NetBSD fdformat(1) -f device
FreeBSD	device argument	FreeBSD requires a device operand, either a full path such as /dev/fd0 or an abbreviated name such as fd0. Solnix devname is optional and defaults to the first diskette drive, if one exists. Source: FreeBSD fdformat(8) SYNOPSIS, DESCRIPTION; Solnix fdformat(1) OPERANDS
FreeBSD	`-v` meaning	Solnix `-v` verifies each block after formatting. FreeBSD `-v` does not format at all and only verifies. A FreeBSD script that uses `-v` to check a disk would format it on Solnix. Source: Solnix fdformat(1) -v; FreeBSD fdformat(8) -v
FreeBSD, NetBSD	verification default	FreeBSD and NetBSD verify after formatting unless `-n` is given. On Solnix, verification happens only when `-v` is given, and the page documents no `-n`. Source: FreeBSD fdformat(8) -n; NetBSD fdformat(1) -n, DESCRIPTION; Solnix fdformat(1) -v, DESCRIPTION
FreeBSD	confirmation prompt and `-q`	Solnix `-q` only suppresses status messages. `-f` is what skips the confirmation. FreeBSD `-q` suppresses output and also skips confirmation. FreeBSD `-y` skips confirmation but still reports status. Source: Solnix fdformat(1) -q, -f; FreeBSD fdformat(8) -q, -y
FreeBSD, NetBSD	file system creation	Solnix writes a SunOS label by default. With `-t` dos (or `-d`) it also puts an MS-DOS file system on the media. FreeBSD and NetBSD only low-level format. Use newfs_msdos(8) (and newfs(8) on FreeBSD) afterwards. Source: Solnix fdformat(1) DESCRIPTION, -t dos; FreeBSD fdformat(8) DESCRIPTION; NetBSD fdformat(1) DESCRIPTION
NetBSD	`-t` meaning	Solnix `-t` takes dos or nec and selects the file system to install. NetBSD `-t` type names a diskette entry in `/etc/floppytab` whose parameters are used for formatting. Source: Solnix fdformat(1) -t dos, -t nec; NetBSD fdformat(1) -t type
NetBSD	`-B` meaning	Solnix `-B` filename installs a boot loader on an MS-DOS diskette and only works with `-d` or `-t` dos. NetBSD `-B` nbps sets the number of bytes per sector. Source: Solnix fdformat(1) -B; NetBSD fdformat(1) -B nbps
FreeBSD, NetBSD	density selection	Solnix selects density with fixed flags: `-D`, `-E`, `-H`, and `-M` with `-t` nec. FreeBSD uses `-f` fmt or `-s` fmtstr. NetBSD sets explicit geometry with `-B`, `-S`, `-T`, `-C`, `-P`, `-G`, `-X` and `-I`, or a named `-t` type. Source: Solnix fdformat(1) -D, -E, -H, -M; FreeBSD fdformat(8) -f, -s; NetBSD fdformat(1) OPTIONS
FreeBSD	exit status	FreeBSD documents exit 0 for success, 1 for formatting errors and 2 for invalid arguments. The Solnix text in the bundle has no EXIT STATUS section, so the manual shown does not say. Source: FreeBSD fdformat(8) EXIT STATUS; Solnix fdformat(1) (no EXIT STATUS in bundle)
FreeBSD, NetBSD	media and manual section	Solnix fdformat also formats PCMCIA memory cards and can unmount file systems first with `-U`. The FreeBSD and NetBSD pages mention only floppy disks. FreeBSD documents it in section 8, Solnix and NetBSD in section 1. Source: Solnix fdformat(1) NAME, -U; FreeBSD fdformat(8) NAME; NetBSD fdformat(1) NAME

Standards

POSIX: fdformat is not a POSIX.1-2024 utility.

Writing portable scripts

Do not script fdformat across systems: -f, -v, -q and -t mean different things on Solnix, FreeBSD and NetBSD. Branch on the OS and use that system's own flags.
Create the file system as a separate step on FreeBSD and NetBSD (newfs_msdos(8), newfs(8)). On Solnix, -t dos does it as part of the format.

Every difference here is taken from the manual pages linked above: Solnix's published page, Linux (man-pages and the GNU and util-linux manuals), FreeBSD, OpenBSD and NetBSD. Each row names its source. Where a manual is silent, this page is too. Compiled 2026-10-26. Found a mistake? Mail hackers@lists.solnix.io.