Man pages › Compared with Linux and the BSDs

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

Solnix /usr/bin/kill is the illumos kill. It takes only the POSIX forms: -s signal_name, -signal_name, -signal_number and -l. The Linux util-linux kill adds -p, -a, -q, -L, -d, --timeout and lookup by process name, none of which the Solnix page documents.

The manual pages

Solnix: kill(1) from pkgs.solnix.illumos-world-man · illumos.org
Linux: kill(1) util-linux-2.42.3
FreeBSD: kill(1) 15.1-RELEASE
OpenBSD: kill(1) 8.0
NetBSD: kill(1) 11.0
Standard: POSIX.1-2024 (IEEE Std 1003.1-2024), kill

What Solnix runs

A default Solnix system runs the illumos kill at /usr/bin/kill. /usr/xpg4/bin/kill is also shipped; the bundle does not describe how it differs. The page says shells have built-in versions of kill (ATTRIBUTES lists csh, ksh, sh and ksh93), so in a script plain kill may not run /usr/bin/kill.

Differences

Compared with	Topic	What differs
Linux	Linux-only options	Solnix kill documents only `-s`, `-l`, `-signal_name` and `-signal_number`. Linux kill also has `-L`/-`-table`, `-a`, `-p`, `-q`/-`-queue`, `-r`, `-d`, `--verbose` and `--timeout`, which do not exist on Solnix. Source: Solnix kill(1) SYNOPSIS, OPTIONS; Linux kill(1) SYNOPSIS, OPTIONS
Linux	process names as operands	Linux kill accepts command names, and pid:pidfd_inode, as operands. The page calls name lookup a local extension. Solnix kill takes only a decimal pid or a job control job ID. Its page says to find process numbers with ps(1). Source: Linux kill(1) SYNOPSIS, DESCRIPTION; Solnix kill(1) OPERANDS
Linux	`-s` argument	On Solnix, `-s` takes a symbolic signal name without the SIG prefix, in any case, or the name 0. Linux `-s` takes a name or a number. kill `-s` 9 is documented on Linux only. On Solnix use kill `-9`. Source: Solnix kill(1) -s; Linux kill(1) -s
Linux	exit status	Solnix exits 0 only if every pid operand matched a process and at least one matching process received the signal. Otherwise it exits >0. Linux kill exits 64 for partial success when several processes are given. Source: Solnix kill(1) EXIT STATUS; Linux kill(1) EXIT STATUS
FreeBSD, OpenBSD, NetBSD	pid `-1`	The BSD pages document pid `-1`: the superuser signals all processes, other users signal all their own processes. The Solnix page refers to kill(2) for negative pids and only spells out 0 (the process group). Source: FreeBSD kill(1) special PIDs; OpenBSD kill(1) special PIDs; NetBSD kill(1) special pids; Solnix kill(1) OPERANDS
FreeBSD, OpenBSD, NetBSD	negative pid and --	Solnix says a negative first pid should be preceded by --. NetBSD says its own kill does not require this, but it is required when no signal is given. FreeBSD and OpenBSD do not mention --. Source: Solnix kill(1) OPERANDS; NetBSD kill(1) DESCRIPTION; FreeBSD kill(1); OpenBSD kill(1)
Linux, NetBSD	`-l` output format	NetBSD `/bin/kill` `-l` uses the POSIX format only when POSIXLY_CORRECT is set. Linux kill `-l` prints one signal per line when output is not a terminal. Solnix kill `-l` writes all supported signal names, and the page gives no format switch. Source: NetBSD kill(1) -l; Linux kill(1) -l; Solnix kill(1) -l

Standards

POSIX: kill is a POSIX.1-2024 utility.
Solnix: /usr/bin/kill, csh, ksh, sh: CSI Enabled; Interface Stability Committed; Standard: see standards(7).
FreeBSD: The kill utility is expected to be IEEE Std 1003.2 (“POSIX.2”) compatible.
OpenBSD: The kill utility is compliant with the IEEE Std 1003.1-2008 (“POSIX.1”) specification. The -signal_name and -signal_number syntax is marked by IEEE Std 1003.1-2008 (“POSIX.1”) as being an X/Open System Interfaces option.
NetBSD: The kill utility is expected to be IEEE Std 1003.2 (“POSIX.2”) compatible.

Writing portable scripts

Use kill -s NAME pid with the signal name and no SIG prefix (for example kill -s HUP 1234). Every page here documents that form.
Put -- before a negative pid (a process group), as Solnix and NetBSD advise.
Do not rely on Linux-only options (-p, --timeout, process names as operands). Look up the pid with ps(1) first.

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.