Skip to main content
Version: v4.23

json

Reads and writes JSON.

Synopsis​

Parser:

json [--merge] [--schema <schema>] [--selector <fieldname[:prefix]>]
     [--schema-only] [--raw] [--unnest-separator <separator>]
     [--ndjson] [--arrays-of-objects] [--precise] [--no-infer]

Printer:

json [-c|--compact-output] [-C|--color-output] [-M|--monochrome-output]
     [--omit-nulls] [--omit-empty-objects] [--omit-empty-lists] [--omit-empty]
     [--arrays-of-objects]

Description​

The json format provides a parser and printer for JSON and line-delimited JSON objects.

Common Options (Parser)​

The JSON parser supports the common schema inference options.

--ndjson (Parser)​

Treat the input as newline-delimited JSON (NDJSON).

NDJSON requires that exactly one event exists per line. This allows for better error recovery in cases of malformed input, as unlike for the regular JSON parser malformed lines can be skipped.

Popular examples of NDJSON include the Suricata Eve JSON and the Zeek Streaming JSON formats. Tenzir supports suricata and zeek-json parsers out of the box that utilize this mechanism.

--precise (Parser)​

Legacy flag. Has the same effect as not providing --merge. This option is incompatible with --merge.

--no-infer (Parser)​

Legacy flag. It is equivalent to the new flag --schema-only.

--arrays-of-objects (Parser)​

Parse arrays of objects, with every object in the outermost arrays resulting in one event each. This is particularly useful when interfacing with REST APIs, which often yield large arrays of objects instead of newline-delimited JSON objects.

--c|--compact-output (Printer)​

Switch to line-delimited JSON output (JSONL/NDJSON).

--C|--color-output (Printer)​

Colorize the output.

The option enables colorizing the output similar to jq by emitting terminal escape sequences that represent colors.

Unlike jq, coloring is currently opt-in. In the future, we will perform TTY detection and colorize the output when write to stdout.

Tenzir honors the NO_COLOR environment variable and won't colorize the output when the variable is present.

--M|--monochrome-output (Printer)​

Disables colored output.

This is currently the default. In the future, we will perform TTY detection and colorize the output when write to stdout. Use this option today if you want to avoid an implicit upgrade to colors in the future.

--omit-nulls (Printer)​

Strips null fields from the output.

Example:

{
  "a": null,
  "b": [42, null, 43],
  "c": {
    "d": null,
    "e": 42
  }
}

With --omit-nulls, this example becomes:

{
  "b": [42, 43],
  "c": {
    "e": 42
  }
}

--omit-empty-objects (Printer)​

Strips empty objects from the output.

Example:

{
  "w": null,
  "x": {},
  "y": {
    "z": {}
  }
}

With --omit-empty-objects, this example becomes:

{
  "w": 42,
}

--omit-empty-lists (Printer)​

Strips empty lists from the output.

Example:

{
  "m": [],
  "n": {},
  "o": {
    "p": []
  }
}

With --omit-empty-lists, this example becomes:

{
  "m": {},
  "o": {}
}

--omit-empty (Printer)​

This options combines all other --omit-* options.

--arrays-of-objects (Printer)​

Prints one array of objects per batch of events arriving at the printer as opposed to printing one object per event.

This is particularly useful when interfacing with REST APIs, which often require sets of events grouped into one JSON object.

Use the batch operator to explicitly control how many events get grouped together in the same array.

Example:

{
  "foo": 1
}
{
  "foo": 2
}

With --arrays-of-objects, this example becomes:

[{
  "foo": 1
},
{
  "foo": 2
}]

Examples​

Read JSON from stdin, either NDJSON or tree-structured:

read json

Write JSON without empty fields to a file:

to file /tmp/result.json write json --omit-empty

Print NDJSON to stdout:

write json -c