Man pages › Compared with Linux and the BSDs

`fsirand(8)` on Solnix vs Linux and the BSDs

On Solnix, fsirand is the illumos command at /usr/sbin/fsirand. It takes only -p and one special device. The FreeBSD and OpenBSD versions also take -b and -f and accept several devices; the NetBSD version has -F and -x instead.

The manual pages

Solnix: fsirand(8) from pkgs.solnix.illumos-world-man · illumos.org
FreeBSD: fsirand(8) 15.1-RELEASE
OpenBSD: fsirand(8) 8.0
NetBSD: fsirand(8) 11.0

What Solnix runs

A default Solnix system runs the illumos fsirand at /usr/sbin/fsirand. No other variants are shipped. The page also installs a file system ID in the superblock.

Differences

Compared with	Topic	What differs
FreeBSD, OpenBSD	`-b` and `-f` missing	Solnix fsirand has only `-p`. FreeBSD and OpenBSD also have `-b` (use the default block size instead of the disklabel value) and `-f` (run even if the file system is not marked clean). The Solnix page documents neither. Source: Solnix fsirand(8) SYNOPSIS, OPTIONS; FreeBSD fsirand(8) -b, -f; OpenBSD fsirand(8) -b, -f
NetBSD	`-F` and `-x` missing	NetBSD fsirand has `-F` (treat special as a file system image) and `-x` constant (XOR a constant into the random number). Solnix has neither. Source: NetBSD fsirand(8) -F, -x; Solnix fsirand(8) OPTIONS
FreeBSD, OpenBSD	number of devices	Solnix fsirand takes exactly one special. FreeBSD and OpenBSD synopses accept one or more special arguments, so a loop over devices in a script is needed on Solnix. Source: Solnix fsirand(8) SYNOPSIS; FreeBSD fsirand(8) SYNOPSIS; OpenBSD fsirand(8) SYNOPSIS
FreeBSD, OpenBSD	read-only mounted file systems	FreeBSD and OpenBSD allow fsirand on an unmounted checked file system or on one mounted read-only. Solnix says only an unmounted file system checked with fsck, with the single exception of the root file system in single-user mode. Source: Solnix fsirand(8) DESCRIPTION; FreeBSD fsirand(8) DESCRIPTION; OpenBSD fsirand(8) DESCRIPTION
FreeBSD, OpenBSD	root file system reboot	Solnix says the system must be re-booted immediately after running fsirand on the root file system in single-user mode. FreeBSD and OpenBSD specify the command reboot `-n`. Source: Solnix fsirand(8) DESCRIPTION; FreeBSD fsirand(8) DESCRIPTION; OpenBSD fsirand(8) DESCRIPTION
FreeBSD, OpenBSD, NetBSD	newfs already randomizes	The FreeBSD and OpenBSD pages say newfs(8) already does the equivalent, so running fsirand on a new file system is unnecessary. NetBSD says newfs has done so since NetBSD 2.0 and calls fsirand no longer relevant. The Solnix page does not say this. Source: FreeBSD fsirand(8) DESCRIPTION; OpenBSD fsirand(8) DESCRIPTION; NetBSD fsirand(8) DESCRIPTION; Solnix fsirand(8) DESCRIPTION
NetBSD	exit status and SIGINFO	NetBSD documents exit zero on success and non-zero on failure, and SIGINFO progress statistics on standard error. The Solnix page documents neither. Source: NetBSD fsirand(8) (exit status, SIGINFO paragraphs); Solnix fsirand(8)
FreeBSD, OpenBSD	memory use	FreeBSD and OpenBSD warn that fsirand may use a lot of memory on large disks with few cylinder groups. The Solnix page has no such caveat and instead points to largefile(7) for files of 2 Gbyte or more. Source: FreeBSD fsirand(8) CAVEATS; OpenBSD fsirand(8) CAVEATS; Solnix fsirand(8) USAGE
Linux	no Linux counterpart	The bundle includes no Linux page for fsirand, so nothing is stated about Linux. Source: Bundle header (counterparts: freebsd, openbsd, netbsd only)

Standards

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

Writing portable scripts

Use only fsirand -p special and one device per call if the script must run on Solnix and the BSDs; -b, -f, -F and -x exist on only some of them.

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.