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JSON.awk

A practical JSON parser written in awk.

https://github.com/step-/JSON.awk

Introduction

JSON.awk is a self-contained, single-file program with no external dependencies. It is similar to JSON.sh, a JSON parser written in Bash -- retrieved on 2013-03-13 to form the basis for JSON.awk. Since then the projects have separated their development paths, each one adding new features that you will not find in the other.

Features

  • Single file without external dependencies
  • Can parse multiple input files within a single invocation (one JSON text per file)
  • Callback interface (awk) to hook into parser and output events
  • Library of practical callbacks (optional)
  • Capture invalid JSON input for further processing
  • Choice of MIT or Apache 2 license
  • JSON.sh compatible (as of 2013-03-13) default output format

Non-features

  • Transforming input values, e.g., string/number normalization

Compatibility with Awk Implementations

Of the many awk implementations around, JSON.awk works better with the POSIX ones and with GNU awk. JSON.awk is routinely tested on Linux with gawk, busybox awk and mawk in this order. I recommend gawk. JSON.awk does not require GNU gawk extensions, and the differences of running gawk with or without the --posix option enabled are minimal, if any. Running with busybox awk requires a simple patch FAQ. Running with mawk requires mawk version 1.3.4 20150503 or higher FAQ.

Supported Platforms

All OS platforms for which a POSIX awk implementation is available. Special cases:

Conformance

There is no official conformance test for the JSON language. Thankfully, some unofficial test suites exist. JSON.awk is tested against the JSONTestSuite.

Test results and comparisons

Installing

Add files JSON.awk and optionally callbacks.awk to your project and follow the examples.

Usage Examples

For full instructions please read the docs. Mawk users please read the FAQ. Busybox awk users also please read the FAQ.

Passing file names as command arguments:

awk -f JSON.awk file1.json [file2.json...]

awk -f JSON.awk - < file.json

cat file.json | awk -f JSON.awk -

Passing file names on stdin:

echo -e "file1.json\nfile2.json" | awk -f JSON.awk

Using callbacks to build a custom application (FAQ 5):

awk -f your-callbacks.awk -f JSON.awk file.json

Applications

  • Opera-bookmarks.awk Extract (Chromium) Opera bookmarks and QuickDial thumbnails. Convert bookmark data to SQLite database and CSV file.

Projects known to use JSON.awk

  • Awk for JSON makes available JSON nested objects as the awk array variable _, e.g. awk's _["person","name"] evaluates to Jason for the JSON object {"person":{"name":"Jason"}}.
  • KindleLauncher a.k.a. KUAL, an application launcher for the Kindle e-ink models, uses JSON.awk to parse menu descriptions.

License

This software is available under the following licenses:

  • MIT
  • Apache 2

Credits

  • JSON.sh's source code, retrieved on 2013-03-13, more than inspired version 1.0 of JSON.awk; without JSON.sh this project would not exist.

  • gron for inspiration leading to library module js-dot-path.awk, and for some test files.

  • JSONTestSuite