Man pages › Compared with Linux and the BSDs

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

On Solnix, join is the illumos join at /usr/bin/join. It is the traditional POSIX join: the first synopsis uses -1/-2/-a/-v, and the second keeps the old -j, -j1 and -j2 as normal options. GNU extras such as -i, -z, --header and --check-order are not in the Solnix page.

The manual pages

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

What Solnix runs

A default Solnix system runs the illumos join at /usr/bin/join, from pkgs.solnix.illumos-world-man. No other variants are shipped. The Linux page in the bundle is GNU coreutils join, which is a different program.

Differences

Compared with	Topic	What differs
Linux	GNU-only options	Linux (GNU) join has `-i`/-`-ignore-case`, `-z`/-`-zero-terminated`, `--header`, `--check-order` and `--nocheck-order`. The Solnix page documents none of them, so scripts using them need a different approach on Solnix. Source: Linux join(1) -i, -z, --header, --check-order, --nocheck-order; Solnix join(1) SYNOPSIS and OPTIONS
Linux	`-o` auto	Linux join accepts the keyword auto for `-o` FORMAT, so the first line of each file sets the number of output fields. The Solnix `-o` list takes only filenumber.fieldnumber elements or 0. Source: Linux join(1) DESCRIPTION (FORMAT 'auto'); Solnix join(1) -o
Linux	`-v` meaning	Solnix `-v` filenumber outputs only the unpairable lines of that file. Linux describes `-v` as like `-a` but suppressing joined lines. Solnix `-v` 1 `-v` 2 together output all unpairable lines. Source: Solnix join(1) -v; Linux join(1) -v
Linux	unsorted input	Solnix says the results are unspecified if input is not in collating order, and offers no order check. Linux says a warning is given if the input is unsorted and some lines cannot be joined, and offers `--check-order`. Source: Solnix join(1) DESCRIPTION, OPERANDS; Linux join(1) DESCRIPTION (Important), --check-order
FreeBSD, OpenBSD, NetBSD	`-j`, `-j1`, `-j2` status	Solnix documents `-j`, `-j1` and `-j2` as ordinary options in a second synopsis. FreeBSD, OpenBSD and NetBSD list them only as historic compatibility options that 'should not be used'. NetBSD's synopsis also shows `-j` taking two arguments, file_number and field. Source: Solnix join(1) SYNOPSIS, OPTIONS -j; FreeBSD join(1) COMPATIBILITY; OpenBSD join(1) STANDARDS; NetBSD join(1) SYNOPSIS, COMPATIBILITY
FreeBSD, OpenBSD, NetBSD	`-a` without an argument	On FreeBSD, OpenBSD and NetBSD, a bare `-a` outputs unpairable lines from both files. On Solnix, `-a` always takes a filenumber, and `-a` 1 with `-a` 2 gives the same result. Source: Solnix join(1) -a; FreeBSD join(1) COMPATIBILITY -a; OpenBSD join(1) STANDARDS -a; NetBSD join(1) COMPATIBILITY -a
NetBSD	space after `-a`	NetBSD requires that the argument to `-a` is not preceded by a space, so write `-a1`. The Solnix page documents `-a` filenumber and shows a form with a space. Source: NetBSD join(1) -a, COMPATIBILITY; Solnix join(1) -a
NetBSD	`-o` and the join field	Solnix `-o` accepts 0 for the join field, and the common field is not printed unless requested. The NetBSD `-o` description lists only file_number.field elements. FreeBSD, OpenBSD and Solnix all document 0. Source: Solnix join(1) -o; NetBSD join(1) -o; FreeBSD join(1) -o; OpenBSD join(1) -o
FreeBSD, OpenBSD, NetBSD	`-o` separators and multiple arguments	FreeBSD, OpenBSD and NetBSD say `-o` list elements may be comma or whitespace separated, and call multiple arguments to one `-o` historic. The Solnix page does not say what separates list elements. Source: FreeBSD join(1) -o, COMPATIBILITY; OpenBSD join(1) -o; NetBSD join(1) -o; Solnix join(1) -o

Standards

POSIX: join is a POSIX.1-2024 utility.
Solnix: Interface Stability: Standard. CSI: Enabled.
FreeBSD: The join command conforms to IEEE Std 1003.1-2001 (“POSIX.1”).
OpenBSD: The join utility is compliant with the IEEE Std 1003.1-2008 (“POSIX.1”) specification.
NetBSD: The join command is expected to be IEEE Std 1003.2 (“POSIX.2”) compatible.
Linux: The Linux page in the bundle has no STANDARDS section.

Writing portable scripts

Use -1 and -2 instead of -j, -j1 or -j2, and avoid a bare -a and multi-argument -o. The BSD pages call these historic options that should not be used.
Sort the inputs to match the join: sort -b style when using default separators, plain sort when using -t. All the pages agree on this, and none of the BSD or Solnix pages offer an order check.

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.