Man pages › Compared with Linux and the BSDs

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

sum(1b) is the illumos BSD-compatibility sum at /usr/ucb/sum. It prints a 16-bit checksum and a size in kilobytes, and the page calls it obsolete. The /usr/bin/sum on PATH is a different program (sum(1)) that returns different checksums.

The manual pages

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

What Solnix runs

The page documents /usr/ucb/sum, which is not the sum on PATH. A default Solnix system runs the illumos /usr/bin/sum, described in sum(1). The NOTES section says the two return different checksums for the same file. The bundle does not include the text of sum(1), so this page cannot say how /usr/bin/sum differs beyond that.

Differences

Compared with	Topic	What differs
Linux, FreeBSD, NetBSD	which sum runs	On Solnix, plain sum resolves to `/usr/bin/sum`, not the `/usr/ucb/sum` documented here. Run `/usr/ucb/sum` explicitly to get this page's behaviour. The counterpart systems document a single sum. Source: Solnix sum(1b) SYNOPSIS and NOTES; header line on PATH
Linux, FreeBSD, NetBSD	no options	Solnix `/usr/ucb/sum` has the synopsis 'sum file...' and documents no options. Linux has `-r` and `-s`/-`-sysv`. NetBSD has `-a`, `-c`, `-n`, `-o` and others. FreeBSD sum has no options in its synopsis, but cksum takes `-o`. Source: Solnix sum(1b) SYNOPSIS; Linux sum(1) -r, -s; NetBSD sum(1) SYNOPSIS; FreeBSD sum(1) SYNOPSIS
Linux	algorithm choice	Linux sum defaults to the BSD algorithm with 1K blocks, and `-s` selects System V with 512-byte blocks. The Solnix page names no algorithm and offers no switch. Source: Linux sum(1) -r, -s, --sysv; Solnix sum(1b) DESCRIPTION
FreeBSD, NetBSD	checksum width and algorithm	FreeBSD and NetBSD sum is cksum defaulting to historic algorithm 1, a 16-bit checksum. Solnix also prints a 16-bit checksum, but its page says the result can differ between machines with 16-bit and 32-bit ints. The BSD pages do not say this. Source: FreeBSD sum(1) DESCRIPTION, -o; NetBSD sum(1) DESCRIPTION, -o; Solnix sum(1b) DESCRIPTION
FreeBSD, NetBSD	output format	BSD sum writes a checksum, a count and the file name. For algorithms 1 and 2 the count is in blocks (1024 and 512 bytes). Solnix prints the checksum and the size in kilobytes. The Solnix page does not say whether the file name is printed. Source: FreeBSD sum(1) DESCRIPTION, -o; NetBSD sum(1) -o; Solnix sum(1b) DESCRIPTION
NetBSD	verification and other digests	NetBSD sum accepts `-c` to verify a list of checksums and `-a` to choose MD5, SHA-1, SHA-2 and other algorithms. Solnix `/usr/ucb/sum` can only calculate and display a checksum. Source: NetBSD sum(1) -a, -c; Solnix sum(1b) DESCRIPTION
FreeBSD, NetBSD	exit status	FreeBSD and NetBSD document exit 0 on success and >0 on error. The Solnix page has no exit status section. Source: FreeBSD sum(1) EXIT STATUS; NetBSD sum(1) DESCRIPTION; Solnix sum(1b)
Linux, FreeBSD, NetBSD	large files and status	The Solnix page refers to largefile(7) for files of 2 Gbyte (2^31 bytes) or more and marks the utility obsolete. The counterpart pages say neither. FreeBSD and NetBSD say sum is provided for compatibility only. Source: Solnix sum(1b) USAGE, NOTES; FreeBSD sum(1) DESCRIPTION; NetBSD sum(1) DESCRIPTION

Standards

POSIX: sum is not a POSIX.1-2024 utility.
FreeBSD: The cksum utility is expected to conform to IEEE Std 1003.2-1992 (“POSIX.2”). The page makes no such statement for sum.

Writing portable scripts

Do not compare sum output across systems or between /usr/bin/sum and /usr/ucb/sum on Solnix: the algorithm, block size and result can differ. Use a cryptographic hash tool for integrity checks.

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.