Man pages › Compared with Linux and the BSDs

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

On Solnix, du is the illumos du at /usr/bin/du. Its single-letter flags differ from Linux and the BSDs: -d means 'do not cross filesystems', not a depth limit, and there is no -c grand total. The default unit is 512-byte blocks, as on the BSDs, while Linux defaults to 1024 bytes.

The manual pages

Solnix: du(1) from pkgs.solnix.illumos-world-man · illumos.org
Linux: du(1) coreutils-full-9.11
FreeBSD: du(1) 15.1-RELEASE
OpenBSD: du(1) 8.0
NetBSD: du(1) 11.0
Standard: POSIX.1-2024 (IEEE Std 1003.1-2024), du

What Solnix runs

/usr/bin/du is the illumos du. /usr/xpg4/bin/du has the same synopsis. It differs in that it acts as though -r is always given and reports an error if it cannot stat files or read directories, which affects the exit status. /usr/bin/du is silent about those conditions unless -r is given. /usr/ucb/du is also shipped, but the bundle does not describe it.

Differences

Compared with	Topic	What differs
all four	`-d` meaning	Solnix `-d` takes no argument and means 'do not cross filesystem boundaries'. On Linux, FreeBSD, OpenBSD and NetBSD, `-d` (`--max-depth` on Linux) limits the depth of entries shown. Solnix has no depth option, only `-s` and `-a`. Source: Solnix du(1) SYNOPSIS and -d; Linux du(1) -d, --max-depth; FreeBSD du(1) -d depth; OpenBSD du(1) -d depth; NetBSD du(1) -d
all four	`-c` grand total	Solnix du has no `-c`. Linux, FreeBSD, OpenBSD and NetBSD use `-c` to print a grand total after all arguments. Source: Solnix du(1) SYNOPSIS and OPTIONS; Linux du(1) -c, --total; FreeBSD du(1) -c; OpenBSD du(1) -c; NetBSD du(1) -c
Linux	default block size	Solnix du reports 512-byte units, rounded up, by default. Linux reports 1024-byte units unless POSIXLY_CORRECT is set, which gives 512. Output from the same command line differs by a factor of two. Source: Solnix du(1) DESCRIPTION (default 512-byte units); Linux du(1) text after the option list (units default to 1024 bytes, or 512 if POSIXLY_CORRECT is set)
all four	BLOCKSIZE environment	The Solnix ENVIRONMENT section lists only LANG, LC_ALL, LC_CTYPE, LC_MESSAGES and NLSPATH. FreeBSD, OpenBSD and NetBSD honour BLOCKSIZE. Linux honours DU_BLOCK_SIZE, BLOCK_SIZE and BLOCKSIZE. The Solnix page does not say BLOCKSIZE has any effect. Source: Solnix du(1) ENVIRONMENT; FreeBSD/OpenBSD/NetBSD du(1) ENVIRONMENT; Linux du(1) DU_BLOCK_SIZE, BLOCK_SIZE, BLOCKSIZE
all four	`-P` and `-l` missing	Solnix du has `-H` and `-L` but no `-P`. Linux, FreeBSD, OpenBSD and NetBSD have `-P` (no symlinks followed). Solnix has no `-l` either. Linux and FreeBSD `-l` counts hard-linked files each time they are found, while Solnix counts a multiply-linked file once. Source: Solnix du(1) SYNOPSIS, NOTES; Linux du(1) -P, -l; FreeBSD du(1) -P, -l; OpenBSD du(1) -P; NetBSD du(1) -P
all four	`-b` bytes and option conflicts	Solnix `-b` reports bytes and implies `-A`. Combining `-b` with `-h`, `-k` or `-m` is an error on Solnix, while `-h`, `-k` and `-m` override each other. FreeBSD, OpenBSD and NetBSD have no `-b`. Linux `-b` is `--apparent-size` `--block-size=1`. Source: Solnix du(1) -b and the paragraph after -x; Linux du(1) -b, --bytes; FreeBSD/OpenBSD/NetBSD du(1) SYNOPSIS
OpenBSD, NetBSD	apparent size (`-A`)	Solnix, Linux and FreeBSD have `-A`, which tallies apparent size rather than allocated blocks. The OpenBSD and NetBSD synopses have no `-A`. Source: Solnix du(1) -A; Linux du(1) -A; FreeBSD du(1) -A; OpenBSD du(1) SYNOPSIS; NetBSD du(1) SYNOPSIS
all four	`-o` flag	Solnix `-o` leaves child directories out of a parent's total and does nothing with `-s`. Linux has `-S` (`--separate-dirs`) for a similar purpose. The FreeBSD, OpenBSD and NetBSD pages have no `-o`. Source: Solnix du(1) -o; Linux du(1) -S, --separate-dirs; FreeBSD/OpenBSD/NetBSD du(1) SYNOPSIS
FreeBSD, OpenBSD, NetBSD	`-r` and error reporting	`/usr/bin/du` on Solnix says nothing about unreadable files unless `-r` is given. FreeBSD, OpenBSD and NetBSD already report them by default; FreeBSD and OpenBSD document `-r` as accepted but ignored. `/usr/xpg4/bin/du` on Solnix always reports. Source: Solnix du(1) -r; FreeBSD du(1) -r, STANDARDS; OpenBSD du(1) -r, STANDARDS; NetBSD du(1) -r
FreeBSD, NetBSD	`-g` and `-m` units	Solnix has no `-g` for 1 GiB blocks. FreeBSD and NetBSD have `-g`. Solnix and NetBSD have `-m` for 1 MiB units, and Linux has `-m`. OpenBSD has neither `-g` nor `-m`. Source: Solnix du(1) SYNOPSIS, -m; FreeBSD du(1) -g, -m; NetBSD du(1) -g, -m; OpenBSD du(1) SYNOPSIS; Linux du(1) -m
Linux, FreeBSD, NetBSD	threshold, exclude and inode options	Solnix du has no size threshold, exclude or inode options. Linux and FreeBSD have `-t` threshold. FreeBSD has `-I` mask and Linux has `--exclude` and `-X`. Linux has `--inodes` and NetBSD has `-i`. Linux also has `--files0-from`, `-0` and `--time`. Source: Linux du(1) -t, --exclude, -X, --inodes, --files0-from, -0, --time; FreeBSD du(1) -t, -I; NetBSD du(1) -i; Solnix du(1) SYNOPSIS
Linux, FreeBSD	human-readable variants	Solnix `-h` scales by 1024 and has no `--si`. Linux and FreeBSD have `--si` for powers of 1000. Linux and FreeBSD also have `-B` to set an arbitrary block size, which Solnix lacks. Source: Solnix du(1) -h; Linux du(1) --si, -B; FreeBSD du(1) --si, -B

Standards

POSIX: du is a POSIX.1-2024 utility.
Solnix: INTERFACE STABILITY: the command line interface of du is Committed. The output of du is Committed.
FreeBSD: The du utility is compliant with the IEEE Std 1003.1-2008 (“POSIX.1”) specification. The flags [-ABIPcdghlmnt], [--libxo], [--si] and the BLOCKSIZE environment variable are extensions.
OpenBSD: The du utility is compliant with the IEEE Std 1003.1-2008 (“POSIX.1”) specification. The flags [-cdhP] and the BLOCKSIZE environment variable are extensions.

Writing portable scripts

Use only -a, -s, -k, -x and -H or -L in portable scripts. Do not use -d, -c, -b, -o, -P or -m, because they differ or are missing between systems.
Do not assume a default unit. Pass -k when you need 1024-byte blocks, since the default is 512 on Solnix and the BSDs and 1024 on Linux.

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.