Man pages › Compared with Linux and the BSDs

`smrsh(8)` on Solnix vs Linux and the BSDs

smrsh is the illumos restricted shell for sendmail's prog mailer. It runs only programs found in /var/adm/sm.bin. FreeBSD smrsh uses /usr/libexec/sm.bin by default, so the allowed-commands directory differs.

The manual pages

Solnix: smrsh(8) from pkgs.solnix.illumos-world-man · illumos.org
FreeBSD: smrsh(8) 15.1-RELEASE

What Solnix runs

A default Solnix system runs the illumos smrsh. The command is not in /usr/bin, /usr/sbin or /sbin, and the page does not give its install path. No other variants are shipped. The page is published by pkgs.solnix.illumos-world-man. The bundle has no Linux, OpenBSD or NetBSD counterpart page.

Differences

Compared with	Topic	What differs
FreeBSD	allowed-command directory	Solnix smrsh confines programs to `/var/adm/sm.bin.` FreeBSD smrsh uses `/usr/libexec/sm.bin` by default. Populate the directory that matches the system. Source: Solnix smrsh(8) DESCRIPTION; FreeBSD smrsh(8) DESCRIPTION
FreeBSD	shell builtins	FreeBSD smrsh also allows the shell builtins exec, exit and echo. The Solnix page mentions no builtins; it says only that programs must be in `/var/adm/sm.bin.` Source: FreeBSD smrsh(8) DESCRIPTION; Solnix smrsh(8) DESCRIPTION
FreeBSD	rejected characters	Solnix rejects , < > \| ; & $ CR and LF. FreeBSD rejects ` < > ; $ ( ) CR and LF as listed. Solnix lists \| and & as rejected, and FreeBSD allows \|\| and && as operators. Solnix lists no parentheses. Source: Solnix smrsh(8) DESCRIPTION (second paragraph); FreeBSD smrsh(8) DESCRIPTION (second paragraph)
FreeBSD	\|\| and && chaining	FreeBSD smrsh allows \|\| and && so a prog mailer can run something like "\|exec `/usr/local/bin/filter` \|\| exit 75". The Solnix page rejects \| and & and documents no such chaining. Source: FreeBSD smrsh(8) DESCRIPTION; Solnix smrsh(8) DESCRIPTION
FreeBSD	procmail advice	The Solnix page lists procmail as a reasonable addition to sm.bin. FreeBSD says including mail filtering programs such as procmail is a very bad idea, because procmailrc lets users run arbitrary programs. Source: Solnix smrsh(8) DESCRIPTION (fourth paragraph); FreeBSD smrsh(8) DESCRIPTION (last paragraph)
FreeBSD	`-c` option	Both systems document the same invocation, smrsh `-c` command. The Solnix page has an OPTIONS section describing `-c`; the FreeBSD page has none. Source: Solnix smrsh(8) SYNOPSIS, OPTIONS -c; FreeBSD smrsh(8) SYNOPSIS
FreeBSD	configurable directory	FreeBSD says the directory is `/usr/libexec/sm.bin` 'by default', which implies it can be changed. The Solnix page names `/var/adm/sm.bin` and does not say it can be changed. Source: FreeBSD smrsh(8) DESCRIPTION; Solnix smrsh(8) DESCRIPTION

Standards

POSIX: smrsh is not a POSIX.1-2024 utility.
Solnix: The Solnix page refers to attributes(7) in SEE ALSO. The trimmed text shows no interface stability table.

Writing portable scripts

Do not hard-code the sm.bin path in scripts or sendmail configuration: it is /var/adm/sm.bin on Solnix and /usr/libexec/sm.bin on FreeBSD.
Do not rely on shell operators such as || or && in |program entries. Solnix smrsh rejects | and &, while FreeBSD allows || and &&.

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.