feat(coreutils): add grep, find and xargs - #441
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Aug 29, 2026
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Three of the largest remaining divergences. `grep -P` does not exist on
macOS; `find`'s `-printf`, `-regextype`, `-delete` and `-newermt` are all
GNU-only and BSD `find` requires an explicit path; and `xargs -r` is
GNU-only while the no-input default is inverted between the two.
`find` and `xargs` are adapters over uutils/findutils. Its entry points
take `&[&str]`, so a non-UTF-8 argument is refused by name rather than
lossily converted: GNU `find` accepts arbitrary bytes in a path, this
cannot, and searching a *different* path than the one asked for is worse
than saying so.
`grep` is a POSIX front-end over `grep-searcher`/`grep-regex`, the engine
ripgrep uses, covering -EFivnclLqwxrhHs, -m, -e, -f and `--`. Two
deliberate departures from GNU:
- No -P. The `regex` crate has no backreferences or lookaround by
design, so -P fails with that explanation rather than with "invalid
option" — a pattern needing it has to be rewritten, not retried.
- Never colourised. Output goes into build logs and gets parsed; a
`--color=auto` that guessed from a tty would make a recipe's
behaviour depend on how it was invoked.
The argument parser is hand-rolled rather than clap because `grep -e -v
file` must treat `-v` as the pattern, which a declarative parser fights.
Line numbers are always counted and only printed under -n: the `UTF8`
sink asks every match for its line number and fails with "line numbers
not enabled" if the searcher was not tracking them — found by running it.
Not planned: `diff`/`cmp`. The `diffutils` crate exposes its algorithms
but keeps its CLI in a private `main`, so wiring it up would mean
reimplementing its argument parsing for the lowest-value pair in the set.
Verified against the host's GNU tools: `find . -name '*.txt'` and
`grep -c`/`grep -v` produce byte-identical output, `find -printf` works
(GNU-only), and `find | xargs` pipelines. `heph tool coreutils list` no
longer errors when piped into `head`.
COREUTILS_VERSION 1 -> 2: the applet set changed.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0181d7hhbYWXT42Z1KQPM29Q
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