Tooling

zawk is more than an interpreter. Its subcommands help people and AI agents look at data, discover functions, and check, format and document programs.

Command	Purpose
zawk inspect FILE	schema, sample rows and column summary of a data file
zawk functions [FILTER]	list builtin functions with signatures and examples
zawk lint	parse and type check a program, JSON diagnostics
zawk fmt	format AWK programs
zawk llm FILE... QUESTION	build an LLM prompt to write a program
zawk init NAME	create a script from a template

zawk inspect

Look at a CSV, TSV, JSON Lines, Parquet, Excel file or database table before writing a program for it:

$ zawk inspect demo.csv
File:    demo.csv
Format:  csv (read with: zawk -i csv -H '...' demo.csv)
Rows:    5
Columns: 3

Schema:
┌───────┬──────┬────────┐
│ field │ name │ type   │
├───────┼──────┼────────┤
│ $1    │ id   │ INT64  │
│ $2    │ name │ STRING │
│ $3    │ age  │ INT64  │
└───────┴──────┴────────┘

Sample (first 5 rows):
...

The summary is like DuckDB's SUMMARIZE: min, max, approx_unique, avg, std, q25, q50, q75, count and null_percentage. Options: -i FORMAT, -o table|markdown, -n ROWS (sample size), --max-rows N. Compressed files, URLs and S3 objects are supported. A CSV header of name:TYPE declares the column type.

zawk functions

zawk functions                 # all functions, grouped by category
zawk functions json            # names containing "json"
zawk functions Crypto          # one category
zawk functions --json trim     # one JSON object per function

zawk lint

zawk lint parses and type checks a program without reading any input, and prints a JSON report. The exit status is 0 when the program is valid (warnings allowed), 1 otherwise.

zawk lint '{ print $1 }'               # program text
zawk lint -f demo.awk                  # program files
echo 'BEGIN { print 1 }' | zawk lint   # from stdin
zawk lint -v n=10 -f top.awk           # n is set on the command line
zawk lint -H -f report.awk             # the run uses -H: $FI[...] is filled
zawk lint -pr -f sum.awk               # also report code that changes meaning in parallel
zawk --lint -f report.awk data.csv     # lint, then run if there is no error

Diagnostics

Code	Meaning
E101	syntax error
E102	invalid token: unterminated string, bad regex literal...
E201	unsupported syntax: @load, @namespace, indirect calls, $$1
E202	arrays of arrays a[i][j] (use a[i,j])
E301	call to an unknown function
E302	wrong number of arguments to a builtin function
E303	a variable used both as an array and as a scalar
E305	assignment to a read-only variable or field
W101	gawk variable with no meaning in zawk (FIELDWIDTHS, FPAT, RT)
W103	f or r used as a name (clashes with f-strings and raw strings)
W105	$FI[...] without -H
W116	$NF-1 is the last field minus 1, not $(NF-1)
W117	field compared with a numeric string ($3 > "100"): a string comparison
W118	printf $0: a % in the data breaks it
W119	FS assigned in a main rule: applies from the next record only
W201	variable read but never set
W202 / W203	printf format with more / fewer arguments than given
W206	variable set but never read (typo: totl += $1 ... print total)
W207	function defined but never called
W301 / W302	NR and END aggregation semantics in parallel mode

zawk fmt

zawk fmt demo.awk              # print the formatted program
zawk fmt -w *.awk              # write files back
zawk fmt --check *.awk         # exit 1 if a file is not formatted (CI)
zawk fmt --indent 2 demo.awk   # or --tabs

Blocks are indented, one statement per line, spaces are normalized; comments, blank lines and literals are kept. The result is checked to parse to the same program as the original.

zawk llm

Builds a prompt with your data's schema and sample, the zawk language notes and your question. See AI integration.

zawk llm -i csv -H demo.csv 'how many adults?' | llm -x

Debugging

zawk --dump-cfg '...'          # untyped control-flow graph
zawk --dump-bytecode '...'     # bytecode
zawk -Binterp '...'            # bytecode interpreter instead of the Cranelift JIT

Inside a program, var_dump(x) prints any value or array to stderr, and log_debug/log_info/log_warn/ log_error write logs controlled by RUST_LOG.