Question 1

Is this a real awk engine?

Accepted Answer

It's a small pure-JavaScript awk interpreter built from scratch — no WASM, no network. It supports BEGIN/END blocks, pattern { action } rules, $0/$1/$N field access, NR/NF special variables, the -F field-separator flag, -v variable assignment, FS/OFS, print and printf, if/else, while, for, length/tolower/toupper/substr/split, arithmetic (+ - * / %), comparisons (== != < > <= >=), logical operators (&& || !), string concatenation, and /regex/ patterns. For features outside this subset (e.g. gawk-only extensions, associative arrays, functions, BEGINFILE/ENDFILE) use awk.js.org or gawk directly.

Question 2

How does the visual builder work?

Accepted Answer

Pick the columns to print (comma-separated, e.g. 1,3), optionally add a condition (e.g. $2 > 100 or /pattern/), optionally choose an aggregation (sum, avg, min, max, count), choose a field separator, and the builder generates a valid awk program AND a copy-ready command `awk -F',' '{print $1,$3}' file`. Each option has a plain-English explanation showing what -F, -v, BEGIN, END, NR, NF, and OFS do in your specific program.

Question 3

What does the reverse explainer do?

Accepted Answer

Paste any awk program (from a Stack Overflow answer or shell history) and the explainer annotates each token: $1, $2 → first/second field; NR → current record number; NF → field count; BEGIN{}/END{} → setup/teardown blocks; -F',' → comma field separator; -v var=val → variable pre-assignment; /pattern/ → regex match; print → output. Each annotation is plain English so non-experts can read the program.

Question 4

How does field separator handling work?

Accepted Answer

Use -F',' (or FS="," in BEGIN) for CSV, -F'	' for TSV, -F':' for /etc/passwd. Default whitespace FS treats runs of spaces/tabs as a single separator and trims leading/trailing — matching awk CLI behavior. Multi-character literal separators (e.g. -F'::') are supported; regex separators (e.g. -F'[,:]' to split on either comma or colon) are also supported by the interpreter.

Question 5

What extra features does this tool have versus awk.js.org?

Accepted Answer

(1) Pure-JS interpreter — instant load, works offline, no WASM. (2) Visual builder that generates valid awk for print columns, filter by pattern, sum/avg/min/max/count. (3) Per-option explanation in plain English. (4) Reverse explainer that annotates a pasted program. (5) Recipe library (10 common one-liners). (6) Sample data library (CSV, TSV, /etc/passwd, access log). (7) GNU vs POSIX toggle changes the example invocation comment. (8) Auto shell-quoting of the program (single quotes, with proper escaping). (9) Copy command + copy output. (10) localStorage history (max 20). (11) Shareable URL with embedded program + input. 100% client-side — your text never leaves the device.

awk Command Builder & Tester

Output

Recipe library

How to use

Output

Recipe library