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jsonwatch — like `watch -d` but for JSON

jsonwatch is a command-line utility that lets you track changes in JSON data delivered by a shell command or a web (HTTP/HTTPS) API. jsonwatch requests data from the source repeatedly at a set interval. It displays the differences when the data changes. It is similar but not identical to how watch(1) with the -d switch works for plain-text data.

jsonwatch has been tested on Debian 12, Ubuntu 24.04, macOS 14, and Windows 10 and Server 2022.

The two previous versions of jsonwatch are preserved in the branch python and haskell.

Installation

Prebuilt binaries are available for Linux and Windows. Binaries are attached to releases on the "Releases" page.

Installing with Cargo

cargo install jsonwatch

Building on Debian and Ubuntu

Follow the instructions to build a static Linux binary of jsonwatch from the source code on recent Debian and Ubuntu.

1. Install Rustup. Through Rustup, add the stable musl libc target for your CPU.

rustup target add x86_64-unknown-linux-musl

2. Install the build and test dependencies.

sudo apt install build-essential expect musl-tools
cargo install just

3. Clone this repository. Build the binary.

git clone https://github.com/dbohdan/jsonwatch
cd jsonwatch
just test
just release-linux

Cross-compiling for Windows

Follow the instructions to build a 32-bit Windows binary of jsonwatch on recent Debian and Ubuntu.

1. Install Rustup. Through Rustup, add the i686 GNU ABI Windows target.

rustup target add i686-pc-windows-gnu

2. Install the build dependencies.

sudo apt install build-essential mingw-w64
cargo install just

3. Configure Cargo for cross-compilation. Add the following in ~/.cargo/config.

[target.i686-pc-windows-gnu]
linker = "/usr/bin/i686-w64-mingw32-gcc"

4. Clone this repository. Build the binary.

git clone https://github.com/dbohdan/jsonwatch
cd jsonwatch
just release-windows

Use examples

Commands

*nix

Testing jsonwatch.

$ jsonwatch -n 1 -c "echo '{ \"filename\": \"'\$(mktemp -u)'\"}'"

{
  "filename": "/tmp/tmp.dh3Y7LJTaK"
}
2020-01-19T18:52:19+0000 .filename: "/tmp/tmp.dh3Y7LJTaK" -> "/tmp/tmp.i4s56VENEJ"
2020-01-19T18:52:20+0000 .filename: "/tmp/tmp.i4s56VENEJ" -> "/tmp/tmp.zzMUSn45Fc"
2020-01-19T18:52:21+0000 .filename: "/tmp/tmp.zzMUSn45Fc" -> "/tmp/tmp.Jj1cKt6VLr"
2020-01-19T18:52:22+0000 .filename: "/tmp/tmp.Jj1cKt6VLr" -> "/tmp/tmp.1LGk4ok8O2"
2020-01-19T18:52:23+0000 .filename: "/tmp/tmp.1LGk4ok8O2" -> "/tmp/tmp.wWulyho8Qj"

Docker process information.

$ jsonwatch -c 'docker ps -a "--format={{json .}}"' -n 1

2020-01-19T18:57:20+0000
    + .Command: "\"bash\""
    + .CreatedAt: "2020-01-19 18:57:20 +0000 UTC"
    + .ID: "dce7fb2194ed"
    + .Image: "i386/ubuntu:latest"
    + .Labels: ""
    + .LocalVolumes: "0"
    + .Mounts: ""
    + .Names: "dreamy_edison"
    + .Networks: "bridge"
    + .Ports: ""
    + .RunningFor: "Less than a second ago"
    + .Size: "0B"
    + .Status: "Created"
2020-01-19T18:57:21+0000 .RunningFor: "Less than a second ago" -> "1 second ago"
2020-01-19T18:57:23+0000
    .RunningFor: "1 second ago" -> "3 seconds ago"
    .Status: "Created" -> "Up 1 second"
2020-01-19T18:57:24+0000
    .RunningFor: "3 seconds ago" -> "4 seconds ago"
    .Status: "Up 1 second" -> "Up 2 seconds"
2020-01-19T18:57:25+0000
    .RunningFor: "4 seconds ago" -> "5 seconds ago"
    .Status: "Up 2 seconds" -> "Up 3 seconds"

Windows

On Windows, -c executes cmd.exe commands.

> jsonwatch -c "type tests\weather1.json"

{
  "clouds": {
    "all": 92
  },
  "name": "Kiev",
  "coord": {
    "lat": 50.43,
    "lon": 30.52
  },
  "sys": {
    "country": "UA",
    "message": 0.0051,
    "sunset": 1394985874,
    "sunrise": 1394942901
  },
  "weather": [
    {
      "main": "Snow",
      "id": 612,
      "icon": "13d",
      "description": "light shower sleet"
    },
    {
      "main": "Rain",
      "id": 520,
      "icon": "09d",
      "description": "light intensity shower rain"
    }
  ],
  "rain": {
    "3h": 2
  },
  "base": "cmc stations",
  "dt": 1394979003,
  "main": {
    "pressure": 974.8229,
    "humidity": 91,
    "temp_max": 277.45,
    "temp": 276.45,
    "temp_min": 276.15
  },
  "id": 703448,
  "wind": {
    "speed": 10.27,
    "deg": 245.507
  },
  "cod": 200
}
2020-01-19T18:51:04+0000 + .test: true
2020-01-19T18:51:10+0000 .test: true -> false
2020-01-19T18:51:23+0000 - .test: false

URLs

Watching a URL works identically on *nix and on Windows.

Weather tracking. (This API no longer works without a key.)

$ jsonwatch -u http://api.openweathermap.org/data/2.5/weather\?q\=Kiev,ua --no-initial-values -n 300

2014-03-17T23:06:19.073790
    + .rain.1h: 0.76
    - .rain.3h: 0.5
    .dt: 1395086402 -> 1395089402
    .main.temp: 279.07 -> 278.66
    .main.temp_max: 279.82 -> 280.15
    .main.temp_min: 277.95 -> 276.05
    .sys.message: 0.0353 -> 0.0083

Geolocation. (Try this on a mobile device.)

$ jsonwatch -u https://ipinfo.io/ --no-initial-values -n 300