Man pages › Compared with Linux and the BSDs

`ln(1b)` on Solnix vs Linux and the BSDs

This page documents /usr/ucb/ln, the BSD-compatibility ln. A default Solnix system puts /usr/bin/ln (illumos) on PATH, not this one. /usr/ucb/ln takes only -f and -s, and its -f means 'allow a super-user hard link to a directory', not 'replace an existing destination' as on Linux and the BSDs.

The manual pages

Solnix: ln(1b) from pkgs.solnix.illumos-world-man · illumos.org
Linux: ln(1) coreutils-full-9.11
FreeBSD: ln(1) 15.1-RELEASE
OpenBSD: ln(1) 8.0
NetBSD: ln(1) 11.0
Standard: POSIX.1-2024 (IEEE Std 1003.1-2024), ln

What Solnix runs

The command on PATH is the illumos /usr/bin/ln. /usr/xpg4/bin/ln and /usr/ucb/ln are also shipped. This page (ln(1b)) describes only /usr/ucb/ln, so the options of /usr/bin/ln and /usr/xpg4/bin/ln are not in this bundle and are not compared here. Call /usr/ucb/ln by full path to get the behaviour below.

Differences

Compared with	Topic	What differs
all four	`-f` meaning	In `/usr/ucb/ln`, `-f` forces a hard link to a directory and is available only to the super-user. On Linux, FreeBSD, OpenBSD and NetBSD, `-f` removes or unlinks an existing destination so the link can be made. A script that uses ln `-sf` to replace a link does not get that behaviour from this page. Source: Solnix ln(1b) -f; Linux ln(1) -f; FreeBSD ln(1) -f; OpenBSD ln(1) -f; NetBSD ln(1) -f
Linux	hard-linking directories	On Solnix `/usr/ucb/ln`, the super-user uses `-f` to hard link a directory. On Linux the option is `-d`, `-F` or `--directory`, and it only lets the superuser attempt the link if the system supports it. Source: Solnix ln(1b) -f; Linux ln(1) -d, -F, --directory
FreeBSD, OpenBSD, NetBSD	hard-linking directories	FreeBSD and NetBSD say directories may not be hardlinked. OpenBSD says hard links may not normally refer to directories. None of the three documents a flag to force it, unlike Solnix `-f`. Source: FreeBSD ln(1) DESCRIPTION; NetBSD ln(1) DESCRIPTION; OpenBSD ln(1) DESCRIPTION; Solnix ln(1b) -f
all four	missing options	The Solnix `/usr/ucb/ln` synopsis has only `-f` and `-s`. It has no `-L` or `-P` (hard links to symlinks), `-n` or `-h` (do not follow a symlink target), `-i`, `-v` or `-w`. Linux also has `-r`, `-t`, `-T`, `-b` and `-S`, which are absent here. The `-L` and `-P` options exist on all four counterparts. Source: Solnix ln(1b) SYNOPSIS and OPTIONS; Linux ln(1) options; FreeBSD ln(1) -L -P -h -i -n -v -w; OpenBSD ln(1) -h -L -n -P; NetBSD ln(1) -L -P -h -i -n -v -w
all four	directory form makes symbolic links	The Solnix page describes the 'pathname... directory' form as making symbolic links in the directory. It does not say what happens without `-s`. The Linux, FreeBSD, OpenBSD and NetBSD pages describe that form for both hard and symbolic links. Source: Solnix ln(1b) DESCRIPTION (third paragraph); Linux ln(1) DESCRIPTION; FreeBSD ln(1) DESCRIPTION; OpenBSD ln(1) DESCRIPTION; NetBSD ln(1) DESCRIPTION
Linux	relative symlinks and self-pointing links	With a bare basename and a directory as the last argument, Solnix ln `-s` makes a link that points to itself ('Too many levels of symbolic links'). The page's workaround is a full path or $PWD. Linux has `-r`/-`-relative` to create links relative to the link location. Source: Solnix ln(1b) NOTES; Linux ln(1) -r, --relative
Linux	existing destinations, backups and environment	Linux ln has `--backup`, `-b`, `-S`, `-i`, and reads SIMPLE_BACKUP_SUFFIX and VERSION_CONTROL. The Solnix page documents no backup or prompt options, no environment variables, and does not say what happens when the destination exists. Source: Linux ln(1) --backup, -S, -i and backup suffix paragraph; Solnix ln(1b) OPTIONS
OpenBSD	exit status	OpenBSD documents that ln exits 0 on success and >0 on error. The Solnix page has no EXIT STATUS section. Source: OpenBSD ln(1) EXIT STATUS; Solnix ln(1b) (no EXIT STATUS section)
FreeBSD	link command	The FreeBSD page also documents link source_file target_file. It takes exactly two non-directory arguments and no options. The Solnix ln(1b) page documents no such command. Source: FreeBSD ln(1) SYNOPSIS and DESCRIPTION; Solnix ln(1b) SYNOPSIS

Standards

POSIX: ln is a POSIX.1-2024 utility. The Solnix ln(1b) page has no STANDARDS section and does not say how /usr/ucb/ln relates to it.
FreeBSD: The ln utility conforms to IEEE Std 1003.2-1992 (“POSIX.2”). The simplified link command conforms to Version 2 of the Single UNIX Specification (“SUSv2”). -h, -i, -n, -v and -w are non-standard, and -F is a FreeBSD extension.
OpenBSD: The ln utility is compliant with the IEEE Std 1003.1-2008 (“POSIX.1”) specification. The flags [-hn] are extensions to that specification.
NetBSD: The ln utility conforms to IEEE Std 1003.2-1992 (“POSIX.2”). -h, -i, -n, -v and -w are non-standard.

Writing portable scripts

Use only -s (and no other flags) in portable scripts. Do not rely on -f: /usr/ucb/ln uses it to force directory hard links, while the other systems use it to replace an existing destination.
Pass full paths as symlink targets, as the Solnix NOTES advise. With a bare basename and a directory last argument, /usr/ucb/ln -s makes a link that points to itself.

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.