Man pages › Compared with Linux and the BSDs

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

On Solnix, mktemp is the illumos mktemp at /usr/bin/mktemp. Its option set matches the OpenBSD page: -t is a flag, not an option with an argument as on FreeBSD and NetBSD. -u creates then unlinks the file, where Linux -u/--dry-run creates nothing. Portable `mktemp -t prefix` calls are the likeliest to break.

The manual pages

Solnix: mktemp(1) from pkgs.solnix.illumos-world-man · illumos.org
Linux: mktemp(1) coreutils-full-9.11
FreeBSD: mktemp(1) 15.1-RELEASE
OpenBSD: mktemp(1) 8.0
NetBSD: mktemp(1) 11.0

What Solnix runs

A default Solnix system runs the illumos mktemp at /usr/bin/mktemp. No other variants are shipped. The Solnix page says the utility appeared in OpenBSD 2.1, and its options and wording closely follow the OpenBSD page.

Differences

Compared with	Topic	What differs
FreeBSD, NetBSD	`-t` takes an argument on the BSDs	On Solnix, `-t` is a plain flag, and the template (if given) must be a single directory component. On FreeBSD and NetBSD, `-t` takes a prefix argument. The Solnix page does not say what `mktemp `-t` prefix` does when the template has no Xs. Source: Solnix mktemp(1) OPTIONS -t, OPERANDS; FreeBSD mktemp(1) SYNOPSIS, -t prefix; NetBSD mktemp(1) SYNOPSIS, -t prefix
Linux	`-u` / `--dry-run`	Solnix `-u` creates the file, then unlinks it before exit, which the page calls a race condition and discourages. Linux `-u` (`--dry-run`) does not create anything and only prints a name. Source: Solnix mktemp(1) -u; Linux mktemp(1) -u, --dry-run
Linux, FreeBSD	long options	Solnix has only the short options `-d`, `-p`, `-q`, `-t` and `-u`. Linux and FreeBSD also accept `--directory`, `--quiet`, `--dry-run` and `--tmpdir`. Linux also has `--help`, `--version` and `--suffix`. OpenBSD and NetBSD, like Solnix, list no long options. Source: Solnix mktemp(1) SYNOPSIS; Linux mktemp(1) options; FreeBSD mktemp(1) OPTIONS; OpenBSD mktemp(1) SYNOPSIS; NetBSD mktemp(1) SYNOPSIS
Linux	`--suffix` and templates not ending in X	Solnix has no `--suffix`. Its template is a filename with Xs appended to it. Linux `--suffix=SUFF` appends text after the Xs, and is implied when TEMPLATE does not end in X. Linux needs at least 3 consecutive Xs in the last component. Source: Solnix mktemp(1) OPERANDS; Linux mktemp(1) DESCRIPTION, --suffix
all four	default template	With no template, Solnix uses tmp.XXXXXX (six Xs) and implies `-t`. Linux and OpenBSD use tmp.XXXXXXXXXX (ten Xs). Linux implies `--tmpdir`. FreeBSD acts as if `-t` tmp was given. NetBSD acts as if `-t` mktemp was given. Source: Solnix mktemp(1) OPERANDS; Linux mktemp(1) DESCRIPTION; OpenBSD mktemp(1) DESCRIPTION; FreeBSD mktemp(1) DESCRIPTION; NetBSD mktemp(1) DESCRIPTION
FreeBSD, NetBSD	multiple templates	Solnix takes at most one optional template. FreeBSD and NetBSD synopses accept `template ...` and can create several files in one call. FreeBSD also allows this together with `-t`. Source: Solnix mktemp(1) SYNOPSIS; FreeBSD mktemp(1) SYNOPSIS, DESCRIPTION; NetBSD mktemp(1) SYNOPSIS, DESCRIPTION
NetBSD	`-p` and TMPDIR precedence	On Solnix, `-p` implies `-t` and a set TMPDIR overrides the `-p` directory. On NetBSD, `-p` applies to every file, and for `-t` it comes before TMPDIR. Without `-p`, a NetBSD template argument is relative to the current directory. Source: Solnix mktemp(1) -p, -t; NetBSD mktemp(1) -p tmpdir, -t prefix
Linux	`-p` and `-t` semantics	Linux `-p` DIR (or `--tmpdir`) interprets TEMPLATE relative to DIR, and the template may contain slashes. Linux marks `-t` deprecated. On Solnix, `-p` implies `-t`, so the template should contain no slashes. The Linux page does not say TMPDIR overrides `-p`. Source: Solnix mktemp(1) -p, -t; Linux mktemp(1) -p, --tmpdir, -t
FreeBSD	`-p` semantics	FreeBSD `-p` tmpdir is used for `-t` only when TMPDIR is unset, and also makes template arguments relative to tmpdir. An empty or omitted tmpdir means use TMPDIR. Solnix `-p` only supplies a prefix directory for `-t` mode. Source: Solnix mktemp(1) -p; FreeBSD mktemp(1) -p tmpdir, --tmpdir
FreeBSD, OpenBSD, NetBSD	exit status	Solnix documents exit 0 on success and 1 on error. FreeBSD and OpenBSD document 0 on success and >0 on error. NetBSD documents 1 on any failure. The Linux page documents no exit status. Source: Solnix mktemp(1) EXIT STATUS; FreeBSD mktemp(1) EXIT STATUS; OpenBSD mktemp(1) EXIT STATUS; NetBSD mktemp(1) EXIT STATUS
Linux	file mode	Solnix creates the file readable and writable only by its owner. Linux creates files u+rw and directories u+rwx, minus umask restrictions. The Solnix page does not mention the umask. Source: Solnix mktemp(1) DESCRIPTION; Linux mktemp(1) DESCRIPTION

Standards

POSIX: mktemp is not a POSIX.1-2024 utility.
Solnix: Interface Stability: Committed.

Writing portable scripts

Always pass a full template ending in Xs, such as `mktemp "${TMPDIR:-/tmp}/prog.XXXXXX"`. Avoid `-t prefix`, which is a flag on Solnix and OpenBSD but takes an argument on FreeBSD and NetBSD.
Do not use -u or --dry-run to get a name safely. It creates nothing on Linux but creates then unlinks on the other systems.

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.