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Show HN: Grev - Thinking Coreutils with Jev

TypeSafe released Grev, a suite of Unix-style filters that run on its Jev models to answer typed questions with calibrated probabilities instead of generating text, keeping the input as the output. The 14 tools include grev (grep), isv (test), tagv (awk), rank (sort), pickv (grep -o), uniqv (uniq), cutv (cut), seek (find), lookv (look/git bisect) and probev (awk), with packages for deb, rpm, apk, Arch, Linux, macOS, FreeBSD and Windows. TypeSafe says a few thousand lines cost fractions of a cent and take seconds, and the tools support flags for parallelism (-J N/-Jmax), per-run budgets (--max-cost), progress with projected cost (-p) and quote confirmation (-Q).

read5 min views1 publishedSep 24, 2026
Show HN: Grev - Thinking Coreutils with Jev
Image: Michielbdejong (auto-discovered)

Unix filters that ask questions instead of matching patterns.

$ cat examples/menu.txt
chicken tikka masala
fresh fruit salad
spaghetti carbonara
tofu stir fry with rice

$ grev 'is a vegan meal' examples/menu.txt
fresh fruit salad
tofu stir fry with rice

The tools run on TypeSafe's Jev models, which answer typed questions with calibrated probabilities instead of generating text. That's why these tools behave like grep, sort or cut: output is always your input. Labels and scores appear only as explicit columns. A few thousand lines cost fractions of a cent and take seconds.

grev --about 'nginx error log' 'says the upstream server timed out' examples/nginx-error.log
journalctl -fu myapp | grev --line-buffered --about 'application log' 'shows the process crashed'
git log --oneline | grev --about 'commit messages' 'fixes a bug'

git diff --cached | isv 'adds a secret or credential' && echo 'refusing to commit' && exit 1

tagv billing technical feature-request other < examples/tickets.txt
tagv --split tickets/ billing technical other < examples/tickets.txt
rank -s -m3 -L 'not urgent|soon|urgent|critical' 'How urgent is the ticket {}?' examples/tickets.txt

man tar | pickv 'how do I list the contents of an archive?'
cutv 'email address' 'phone number' < examples/users.csv
uniqv -c 'Are {1} and {2} the same company?' examples/companies.txt
unwrap examples/memo.txt
seek --verify 'the spend ledger' .

lookv -n --about 'health checks, one per minute' 'reports a failing dependency' examples/lookv-health.log

probev -H -q 'refund: asks for money back' -q 'angry: the writer is angry' < examples/tickets.txt
tool like does
grev grep print the records the model says yes to
isv test answer a yes/no question about the whole input with the exit status
oneof case print which label fits the whole input
tagv awk label every record; --split DIR routes records into files
rank sort sort records by how well they fit, or by ordered levels
pickv grep -o the one line or regex match that best answers a question
uniqv uniq collapse adjacent records that mean the same thing
unwrap fmt re-join hard-wrapped lines
seg csplit split a stream into topic segments
cutv cut cut the CSV/TSV columns that match a description
seek find walk a directory tree to what a description names
lookv look, git bisect find where an ordered input's answer flips, in a few rounds
probev awk print per-record probability columns
jev — config, API key, spend, models, one-off and raw requests

Every tool has --help and a man page. The common flags:

flag meaning
-p progress, with live and projected cost
-Q show the quote and ask first
-J N /-Jmax parallelism
--max-cost per-run budget
  • Packages: deb, rpm, apk, Arch packages and archives for Linux, macOS, FreeBSD and Windows are on thereleases page .packaging/arch/PKGBUILD builds from source.
  • With Go:go install github.com/aurorainfra/grev/cmd/...@latest
  • From source:make && sudo make install , which also installs the man pages and bash/zsh/fish completions.

Everything lives in one file, ~/.grevconfig, in git-config style; the full reference is docs/CONFIG.md (or man grevconfig). jev key set puts your API key there with mode 0600:

[api]
	key = tsk-…                           ; written by `jev key set`
[defaults]
	progress = auto                       ; the -p overlay whenever stderr is a terminal
	jobs = max
	confirmAbove = 0.25                   ; ask before runs quoted above $0.25 (built-in: $1)
[limits]
	daily = 5                             ; spend caps in USD, across all tools
	monthly = 50
[tool "grev"]
	about = application logs              ; per-tool defaults for any long option,
	threshold = 0.7                       ; e.g. how sure the model must be to say yes

Thresholds are set per tool because -t means different things: P(yes) in grev, the minimum confidence of a choice in tagv, a path score in seek.

Manage it with jev config set limits.daily 5 or jev config list --show-origin, and check your spend with jev spend. Command-line flags beat environment variables, which beat the config. In CI, TYPESAFE_API_KEY supplies the key without any file.

Jev charges $0.042 per million input tokens, and output is free. Grepping a 4,000-line source file costs about $0.008.

Nothing big runs by surprise:

  • Any run quoted above confirmAbove ($1 unless configured) asks first. Without a terminal, it refuses.

  • --max-cost and the daily/monthly caps stop a run before it goes over.

  • Closing the output pipe (| head ) stops the spending.

  • docs/DESIGN.md: how the tools phrase questions and why, the evals, flag conventions and the cost model.

  • docs/CONFIG.md: configuration in depth.

  • Man pages:grev-tools(7) ,grevconfig(5) , and one per tool.

Licensed under either of Apache License, Version 2.0 or MIT license, at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

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