liszt

(noun) : Franz?!

A from-scratch C11 reimplementation of GNU ls(1). Byte-identical output (parity target: coreutils 9.11), faster on every workload measured. Also installs as lz, which is easier to type than ls.

Why

ls spends its time in a handful of hot loops: collation, per-entry stat calls, quoting analysis, and LS_COLORS suffix matching. liszt keeps GNU's exact output semantics - decode_switches staging, the stat economy of check_stat, quotearg's control flow, dired byte accounting - and swaps the engines underneath: MSD radix sorts (byte, strxfrm-transformed, and numeric-key) with the scalar comparator kept as a verification oracle, SIMD span kernels in width and multibyte scanning, a folded-final-byte suffix table for color classification, and a thread pool over the per-entry stat phase with structurally deterministic output.

A golden suite diffs liszt against a pinned GNU ls built from source - stdout, stderr, and exit codes, across locales, quoting styles, and terminal-dependent defaults - plus a differential fuzzer and syscall-budget assertions (-U does zero per-entry stats; -l does exactly one statx and one llistxattr per entry; statless color schemes stat once).

Measured

hyperfine over the nine required workloads, warm cache, 100k-entry directories, vs GNU ls 9.11 built from source on the same machine. Linux box: x86-64, tmpfs. macOS box: Apple M5 Pro, APFS. Full runs with error bars and machine metadata are stored under bench/release/.

workload	vs ls 9.11 (x86-64)	vs ls 9.11 (arm64)
100k flat, LC_ALL=C	1.7x	1.5x
100k flat, UTF-8 locale	1.3x	2.0x
100k -l	2.7x	1.1x
100k --color=always -F	3.2x	2.0x
deep tree -R	1.2x	1.0x
100k -S	1.9x	1.6x
100k -t	1.8x	1.9x
100k -U	1.3x	1.2x
50-entry dir (startup)	1.0x	1.0x
100k --dired -l	2.6x	1.2x

Install

Homebrew (macOS, Linuxbrew):

brew install tenseleyflow/tap/liszt

Arch, from the AUR:

paru -S liszt           # or: yay -S liszt

or clone https://aur.archlinux.org/liszt.git and run makepkg -si. Arch's mtools package owns /usr/bin/lz, so the Arch package installs liszt and its man page but not the lz alias; create your own (ln -s liszt ~/.local/bin/lz) if you don't use mtools. The same PKGBUILD ships in packaging/. Release tarballs with checksums are on the releases page.

From source:

./configure
make
make check                  # unit + golden parity + fuzz smoke
                            # (builds GNU ls 9.11 once as the oracle)
make install                # liszt + lz + man pages

Requires a C11 compiler, GNU make, and libc only. Runs on Linux (glibc and musl), macOS, and FreeBSD.

Parity notes

The full GNU ls 9.11 flag surface is implemented and pinned: every short flag and every long_options[] entry is exercised against the reference build with byte-identical stdout and matching exit codes. Diagnostics reproduce GNU's quoting (quotef vs quoteaf, locale quotes, argmatch listings) and its exit-code split (argmatch errors exit 1, getopt errors exit 2).

One intentional deviation is carried, with its own regression registry (tests/golden/deviations/): GNU assigns a rejected display width into an unsigned type before its clamp, so names containing control bytes or invalid multibyte sequences in multibyte locales wrap GNU's column arithmetic. liszt honors the intended clamp (width 0). Quoted styles and -q are unaffected, and the registry asserts the oracle still differs so an upstream fix fails loudly.

Platform notes: Unicode width decisions mirror gnulib's per-platform REPLACE_WCWIDTH probe (configure runs the same conformance test); printability is libc iswprint everywhere, matching c32isprint's dispatch. Birth times use statx with GNU's ? fallback where the filesystem has none.

Extensions

v0.2 adds the modern-replacement surface, all off by default: with no extension flag, output stays byte-identical to GNU ls and the whole parity matrix runs unchanged. Flags use eza-compatible names and match by exact spelling only (no abbreviation).

• --icons[=WHEN] - Nerd-Font icons from compiled-in tables (933 curated mappings), resolved from the name and dirent type alone: no stat, no directory reads. LS_ICONS overrides per suffix, filename, directory, or filetype label; LISZT_ICONS_OSC66=1 wraps glyphs in kitty's text-sizing protocol for terminal-guaranteed width. Requires a Nerd Font installed on the system, or the terminal draws boxes - fontconfig falls back per glyph, so any Nerd Font works regardless of the terminal's configured family (fc-list :charset=e5ff family should be non-empty).
• --tree - structural tree with --level=N, --tree-limit=N ("... K more" collapsing), --tree-glyphs=unicode|ascii|auto. One directory descriptor open at any depth: a 100k-node tree lists under ulimit -n 16 with identical bytes. The full sort/filter/color/icon surface applies per sibling list; -l works with metadata on the left.
• --color=full - eza's whole metadata theme: colored permission bits, link counts, your-user highlighting, magnitude-gradient sizes, dates, inodes, plus eza's filename classes where LS_COLORS is silent. Exact spelling only; stripping the SGR reproduces --color=always byte for byte.
• --theme=NAME - 23 built-in 24-bit presets (catppuccin, dracula, gruvbox, kanagawa, nord, monokai, everforest, rose-pine, tokyonight, solarized, one-dark, ...) compiled in; eza makes you download these as YAML files. LISZT_THEME sets the default, LISZT_COLORS overrides single keys in eza's EZA_COLORS grammar. No config file: zero startup cost.
• --git - a status column with zero dependencies: liszt parses .git/index itself (v2-v4, SHA-256 repos, linked worktrees) and compares stat data - nothing is hashed, adding a constant ~30 syscalls per repo and none per entry. --git-ignore hides ignored entries through a from-scratch wildmatch engine; --no-git suppresses. Limits are documented in liszt(1), not glossed over: staged-only changes read as clean.

Measured against eza (the fastest of the modern replacements), same machines as above, artifacts under bench/release/:

workload	vs eza (x86-64)	vs eza (arm64)
100k --icons --color -1	4.3x	10.4x
100k-node --tree	16.2x	12.7x
200k-file repo -l --git	11.1x	15.0x

Extension cost against plain liszt on the same lanes stays gated: icons within 10% on the color lane, --tree within 15% of -R -1, --git within 2x of -l (measured ~10%).

Debug surface

LISZT_DEBUG_PLAN (selected engines), LISZT_DEBUG_STATS (radix and memo counters), LISZT_DEBUG_VERIFY (optimized engines cross-checked against the scalar oracle; the test harness sets it on every run), LISZT_FORCE_SCALAR, LISZT_PARALLEL_MIN, LISZT_PARALLEL_WORKERS.

License

GPL-3.0-or-later. Portions are ported from GNU coreutils and gnulib (mpsort, uniwidth tables, quotearg control flow); see source headers.