json-pipe-cli

json-pipe-cli is a simple CLI for reading JSON from stdin, extracting nested keys, and printing the result to stdout. It supports robust error handling for empty pipes or unexpected TTY usage.

Features

• Read JSON input from stdin.
• Extract one or more nested properties via -k|--keys flags.
• Clear error messages and distinct exit codes:
  • 666: TTY input is not allowed (no pipe provided).
  • 999: Pipe provided but no data received (empty input).
  • 111: Other runtime or parsing errors.

Installation

Install globally with npm:

npm install -g json-pipe-cli

Or add to your project as a dependency:

npm install --save json-pipe-cli

CLI Usage

Basic JSON parsing

Read JSON from a file or other command and pretty-print the entire object:

cat data.json | json-pipe-cli

Output:

Parsed JSON:
------------------------------------------------
{ "foo": { "bar": 123 }, "baz": true }

Extract nested keys

Use -k or --keys followed by one or more property names to drill into the object:

echo '{"foo":{"bar":123}}' | json-pipe-cli -k foo bar

Output:

Parsed JSON value for json["foo"]["bar"]:
------------------------------------------------
123

Help on missing pipe

If you run json-pipe-cli without piping data, it will exit with code 666 and display a helpful message:

$ json-pipe-cli
ERROR:
------------------------------------------------
TTY mode isn't allowed for this application

Exit Codes

Code	Condition
0	Successful parsing and output
666	No pipe provided (TTY input not allowed)
999	Pipe provided but received no data
111	JSON parsing error or other runtime failure