Man pages › Compared with Linux and the BSDs

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

On Solnix, uuidgen is the illumos /usr/bin/uuidgen. It prints one UUID, random (version 4) by default, and has only -r, -t and -o. Linux, FreeBSD and NetBSD all use other flags: -n, -s and -c mean different things or are missing, and there is no count option.

The manual pages

Solnix: uuidgen(1) from pkgs.solnix.illumos-world-man · illumos.org
Linux: uuidgen(1) util-linux-2.42.3
FreeBSD: uuidgen(1) 15.1-RELEASE
NetBSD: uuidgen(1) 11.0

What Solnix runs

A default Solnix system runs the illumos uuidgen at /usr/bin/uuidgen. No other variants are shipped. The page is published in pkgs.solnix.illumos-world-man.

Differences

Compared with	Topic	What differs
FreeBSD	default UUID version	Solnix uuidgen with no options makes a random (DCE version 4) UUID. FreeBSD uuidgen by default makes a DCE version 1 UUID, and needs `-r` to get a random version 4 one. Source: Solnix uuidgen(1) DESCRIPTION; FreeBSD uuidgen(1) DESCRIPTION, -r
Linux	default UUID version	Solnix always defaults to a random UUID. Linux defaults to random only if a high-quality random number generator is present, and otherwise picks a time-based UUID. Source: Solnix uuidgen(1) DESCRIPTION; Linux uuidgen(1) DESCRIPTION
NetBSD	default UUID version	The NetBSD page does not say which UUID version the default is, so a script cannot assume it matches Solnix's random version 4. Source: NetBSD uuidgen(1) DESCRIPTION
FreeBSD, NetBSD	generating several UUIDs	FreeBSD and NetBSD have `-n` count (and `-1` for one-at-a-time) to print several UUIDs. Solnix has no count option, so a script must call uuidgen once per UUID. Source: FreeBSD uuidgen(1) -n, -1; NetBSD uuidgen(1) -n, -1; Solnix uuidgen(1) SYNOPSIS
Linux	`-n` meaning and count	On Linux, `-n` (`--namespace`) selects the namespace for MD5 or SHA1 hash-based UUIDs, and the count is `-C` (`--count`). On Solnix, `-n` does not exist. Source: Linux uuidgen(1) -n, -C; Solnix uuidgen(1) SYNOPSIS
Linux	`-o` missing on Linux	Solnix `-o` filename writes output to a file. The Linux page lists no `-o` option, so a script using it fails there. Use shell redirection instead. Source: Solnix uuidgen(1) -o; Linux uuidgen(1) OPTIONS
Linux, NetBSD	`-s` meaning	Solnix has no `-s`. On Linux, `-s` (`--sha1`) selects a hash-based UUID. On NetBSD, `-s` prints UUIDs as initialized C structures instead of the standard string. Source: Linux uuidgen(1) -s, --sha1; NetBSD uuidgen(1) -s; Solnix uuidgen(1) SYNOPSIS
FreeBSD, NetBSD	`-t` (time-based) option	Solnix and Linux accept `-t` to force a time-based UUID. The FreeBSD and NetBSD synopses have no `-t`. FreeBSD's default is already version 1. Source: Solnix uuidgen(1) -t; Linux uuidgen(1) -t, --time; FreeBSD uuidgen(1) SYNOPSIS; NetBSD uuidgen(1) SYNOPSIS
NetBSD	`-r` (random) option	Solnix, Linux and FreeBSD accept `-r` for a random UUID. The NetBSD synopsis has no `-r`. Source: Solnix uuidgen(1) -r; Linux uuidgen(1) -r; FreeBSD uuidgen(1) -r; NetBSD uuidgen(1) SYNOPSIS
Linux	hash-based and sortable UUIDs	Linux can make MD5 or SHA1 name-based UUIDs (`--md5`, `--sha1` with `--namespace` and `--name`) and time-sortable ones (`-6`, `-7`). The Solnix page documents none of these. Source: Linux uuidgen(1) -m, -s, -n, -N, -6, -7; Solnix uuidgen(1) SYNOPSIS
FreeBSD	compact output	FreeBSD `-c` prints a compact UUID without hyphens. Solnix has no `-c` and its page documents no way to drop the hyphens. Source: FreeBSD uuidgen(1) -c; Solnix uuidgen(1) SYNOPSIS
Linux, FreeBSD, NetBSD	exit status	Solnix documents exit 0 on success and >0 on failure. FreeBSD documents the same. The Linux and NetBSD pages have no exit status section. Source: Solnix uuidgen(1) EXIT STATUS; FreeBSD uuidgen(1) EXIT STATUS; Linux uuidgen(1); NetBSD uuidgen(1)

Standards

POSIX: uuidgen is not a POSIX.1-2024 utility.
Solnix: Interface Stability: Uncommitted.
Linux: CONFORMING TO: OSF DCE 1.1.
FreeBSD: The page has no STANDARDS section. HISTORY: first appeared in FreeBSD 5.0.
NetBSD: The page has no STANDARDS section. HISTORY: first appeared in NetBSD 3.0.

Writing portable scripts

Run plain `uuidgen` with no options and redirect with the shell (`uuidgen > file`) instead of -o. -o is missing on Linux, and the default version differs between systems (random on Solnix, version 1 on FreeBSD).
For several UUIDs, call uuidgen in a loop. -n means a count on FreeBSD and NetBSD, a namespace on Linux, and does not exist on Solnix.

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.