Formatting JSON for readability
Charly's Column – JSON
Armed with just json.tool and jq, Charly preps the JSON data delivered by his Philips Hue bridge so that even humans can read it – an essential step towards improving the usability of his home automation system.
Some time ago [1], I briefly talked about how I use the measured values from a lux sensor to control a Hue lighting system. In redecorating my hallway, I added some new lights and removed others. I couldn't remember the light sources' IDs, so I asked the Hue bridge to dump the configuration. What I got was hard-core JSON, but unfortunately not in a human-readable format (Figure 1).
There are plenty of tools to make JSON readable. I started with what I already had in place, json.tool
, which the Python installation had dumped on my hard disk. I wrote its neatly formatted output to a file in /tmp
for further processing (Listing 1).
Listing 1
JSON Query
$ curl --request GET 10.0.0.10/api/w25-4kqL7d|python -m json.tool > /tmp/hue.all
Listing 2
Light Source Script
01 #! /bin/bash 02 WDIR=/usr/local/shellscripts/lux 03 TMPDIR=/tmp 04 HUEBRIDGE=10.0.0.10 05 USER=w25-4kqL7d 06 07 for i in $(seq 1 20); do 08 echo "trying light $i"; 09 LAMPTEST=$(jq -r -M ".lights.\"$i\".name" /$TMPDIR/hue.all); 10 if [ "$LAMPTEST" != "null" ]; then 11 echo "Light $i exists: $LAMPTEST" 12 fi 13 done
However, I didn't need the data in Python; I wanted to use the output in a small Bash script. This prompted me to continue processing with jq
[2]. The tool claims to be a kind of sed
, awk
, and grep
for JSON. I wanted to find out the current IDs for my light sources, as well as discover their plain text names. Thanks to jq
, a tiny script (Listing 2) is all it takes to do this. When I ran it, it gave me the output shown in Listing 3.
Listing 3
Script Output
Light 4 exists: LR_ceiling_desk Light 5 exists: LR_ceiling_sofa Light 6 exists: ColorWall1 Light 7 exists: Hall_1F Light 8 exists: Hall_2F Light 9 exists: Hall_3F Light 10 exists: LRTinkeringCorner
The reason why IDs 1
to 3
do not exist is because I dismantled the lights and removed them from the Hue app. The Hue bridge has no reason to re-sort the remaining IDs – which is fortunate, because that would cause total chaos every time I changed a lamp. As jq
once again underlines: The shorter a tool's name is; the more important and powerful it is. Lights on!
Infos
- "Charly's Column – Hue and Rasp Pi" by Charly Kühnast, Linux Magazine, issue 218, January 2019, p.39, https://www.linux-magazine.com/Issues/2019/218/Hue-and-Rasp-Pi/(language)/eng-US
- jq: https://stedolan.github.io/jq/
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
![Learn More](https://www.linux-magazine.com/var/linux_magazin/storage/images/media/linux-magazine-eng-us/images/misc/learn-more/834592-1-eng-US/Learn-More_medium.png)
News
-
Canonical Offers 12-Year LTS for Open Source Docker Images
Canonical is expanding its LTS offering to reach beyond the DEB packages with a new distro-less Docker image.
-
Plasma Desktop 6.1 Released with Several Enhancements
If you're a fan of Plasma Desktop, you should be excited about this new point release.
-
SUSE Offers CentOS 7 Support with Liberty Linux Lite
SUSE's Liberty Linux support offering now includes CentOS 7, which means businesses won't be forced to migrate those servers for some time.
-
Ubuntu's App Center Finally Supports Local Installs Again
If you regularly download .deb files and would prefer a GUI method of installing, Ubuntu has your back.
-
AlmaLinux Now Supports Raspberry Pi 5
If you're looking to create with the Raspberry Pi 5 and want to use AlmaLinux as your OS, you're in luck because it's now possible.
-
Kubuntu Focus Releases New Iterations of Ir14 and Ir16 Laptops
If you're a fan of the Kubuntu Focus laptops or have been waiting for the right time to purchase one, that time might be now.
-
NixOS 24.05 Is Ready for Prime Time
The latest release of NixOS (Uakari) has arrived and offers its usual reproducible, declarative, and reliable goodness.
-
Linux Lite 7.0 Officially Released
Based on Ubuntu 24.04 and kernel 6.8, Linux Lite version 7 now offers more options than ever.
-
KaOS Linux 2024.05 Adds Bcachfs Support and More
With updates all around, KaOS Linux now includes support for the bcachefs file system.
-
TUXEDO Computers Unveils New Iteration of the Stellaris Laptop Line
The Stellaris Slim 15 is the 6th generation and includes either an AMD or Intel CPU