Man pages › Compared with Linux and the BSDs

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

ps(1b) documents the BSD-style /usr/ucb/ps, not the /usr/bin/ps that is on PATH by default on Solnix. It has a small fixed set of flags and no -o, -p or -A. Several letters mean something different from the BSDs: -r filters rather than sorts, -U is obsolete and prints nothing, and -g and -n do not exist on the BSDs.

The manual pages

Solnix: ps(1b) from pkgs.solnix.illumos-world-man · illumos.org
Linux: ps(1) procps-4.0.6
FreeBSD: ps(1) 15.1-RELEASE
OpenBSD: ps(1) 8.0
NetBSD: ps(1) 11.0
Standard: POSIX.1-2024 (IEEE Std 1003.1-2024), ps

What Solnix runs

A default Solnix system runs the illumos ps at /usr/bin/ps. This page describes the other variant, /usr/ucb/ps, and the bundle has no text for /usr/bin/ps. For the options of the PATH command, see ps(1). Everything below about Solnix applies only if you run /usr/ucb/ps explicitly.

Differences

Compared with	Topic	What differs
FreeBSD, OpenBSD, NetBSD	`-r` meaning	Solnix `/usr/ucb/ps` `-r` restricts the listing to running and runnable processes. On OpenBSD and NetBSD, `-r` sorts by CPU usage. On FreeBSD, `-r` changes the sort order. None of them filters by state. Source: Solnix ps(1b) -r; OpenBSD ps(1) -r; NetBSD ps(1) -r; FreeBSD ps(1) DESCRIPTION (-m, -r, -u and -v change the sort order)
FreeBSD, OpenBSD, NetBSD	`-U` meaning	Solnix `/usr/ucb/ps` `-U` is obsolete: it has no effect and makes ps exit without printing a listing. On FreeBSD, OpenBSD and NetBSD, `-U` user selects processes by user. A script using ps `-U` user gets no output from `/usr/ucb/ps.` Source: Solnix ps(1b) -U; FreeBSD ps(1) SYNOPSIS (-U user); OpenBSD ps(1) -U; NetBSD ps(1) -U
FreeBSD, OpenBSD, NetBSD	`-A`, `-a` and `-x` selection	Solnix has no `-A`. `-a` adds other users' processes, `-x` adds processes without a controlling terminal, and `-a` `-x` together show everything. FreeBSD and NetBSD define `-A` as `-a` plus `-x`. OpenBSD `-A` shows all users including those without a terminal. Source: Solnix ps(1b) DESCRIPTION, -a, -x; FreeBSD ps(1) -A; NetBSD ps(1) -A; OpenBSD ps(1) -A, -a
FreeBSD, OpenBSD, NetBSD	`-g` and `-n`	Solnix `-g` shows process group leaders, which are hidden without it. `-n` replaces USER with a numeric UID. The FreeBSD and NetBSD option lists have no `-g` or `-n`, and OpenBSD documents both as not supported. Source: Solnix ps(1b) -g, -n; OpenBSD ps(1) STANDARDS ([-dfgn] not supported); FreeBSD ps(1) SYNOPSIS; NetBSD ps(1) SYNOPSIS
all four	no `-o`, `-O`, `-p` or `-L`	The Solnix `/usr/ucb/ps` page has only canned displays (`-l`, `-u`, `-v`). It documents no `-o` or `-O` keyword lists, no `-L`, and no `-p`. A process ID is a final bare argument (num). Linux, FreeBSD, OpenBSD and NetBSD all document `-o`. Source: Solnix ps(1b) SYNOPSIS, num; Linux ps(1) NOTES (-o and -O); FreeBSD ps(1) -o, -p; OpenBSD ps(1) -o, -p; NetBSD ps(1) -o, -p
FreeBSD, OpenBSD, NetBSD	column names in `-u` and `-v`	Solnix `-u` shows USER, %CPU, %MEM, SZ, RSS and START. OpenBSD and NetBSD `-u` use vsz where Solnix uses SZ. Solnix `-v` shows SIZE, %CPU, %MEM and RSS, a much shorter list than the BSD `-v` keyword list. Source: Solnix ps(1b) -u, -v; OpenBSD ps(1) -u, -v; NetBSD ps(1) -u, -v
OpenBSD, NetBSD	`-u` and `-v` sort side effects	On OpenBSD and NetBSD, `-u` implies `-r` and `-v` implies `-m`. The Solnix page describes no sort order or side effect for `-u` or `-v`. Source: OpenBSD ps(1) -u, -v; NetBSD ps(1) -u, -v; Solnix ps(1b) -u, -v
FreeBSD, OpenBSD, NetBSD	`-t` argument form	Solnix `-t` takes one terminal as a device file name (tty04, term/14) or, for tty names, just the digits (04). FreeBSD `-t` takes a comma-separated list. NetBSD uses ? for processes with no terminal. Source: Solnix ps(1b) -t; FreeBSD ps(1) SYNOPSIS (-t tty[,tty...]); NetBSD ps(1) -t
OpenBSD	`-w` width	Solnix `-w` uses 132 columns instead of 80, and `-ww` uses unlimited width. Wide output can be seen only by a superuser or the process owner. OpenBSD `-w` uses 132 columns instead of the window size. The Solnix page documents no COLUMNS variable. Source: Solnix ps(1b) -w; OpenBSD ps(1) -w, ENVIRONMENT (COLUMNS)
Linux	option syntax and default selection	Solnix says its options are combined into the first argument, with num last. Linux ps accepts Unix options with a dash, BSD options without one, and GNU long options. Linux warns that ps `-aux` can be read as `-a` plus user x. By default Linux selects processes of the same euid on the same terminal. Source: Solnix ps(1b) OPTIONS, num; Linux ps(1) DESCRIPTION, NOTES (ps -aux)
Linux	environment variables	Linux ps reads PS_FORMAT, PS_PERSONALITY, CMD_ENV, COLUMNS, LINES, POSIXLY_CORRECT and others. The Solnix page lists no environment variables for `/usr/ucb/ps.` Source: Linux ps(1) ENVIRONMENT VARIABLES; Solnix ps(1b) (no ENVIRONMENT section)

Standards

POSIX: ps is a POSIX.1-2024 utility. The Solnix ps(1b) page for /usr/ucb/ps has no STANDARDS section.
Linux: This ps conforms to Version 2 of the Single Unix Specification, The Open Group Technical Standard Base Specifications, Issue 6, IEEE Std 1003.1, 2004 Edition, X/Open System Interfaces Extension [UP XSI] and ISO/IEC 9945:2003.
OpenBSD: Compliant with IEEE Std 1003.1-2008 (“POSIX.1”) except that -G is unsupported and -p, -t and -U accept only single arguments. Of the X/Open System Interfaces flags, -d, -f, -g and -n are not supported, and -e, -l and -u behave differently.

Writing portable scripts

On Solnix call /usr/bin/ps (the PATH default) in scripts, not /usr/ucb/ps. The ucb page documents no -o, -p or -A.
Avoid -r, -U, -g, -n and -w in portable scripts, because their meaning differs or they are missing. If you use -o, stick to the POSIX keywords listed in OpenBSD's STANDARDS section, such as pid, ppid, comm, args and time.

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.