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.
News
-
Linux Servers Targeted by Akira Ransomware
A group of bad actors who have already extorted $42 million have their sights set on the Linux platform.
-
TUXEDO Computers Unveils Linux Laptop Featuring AMD Ryzen CPU
This latest release is the first laptop to include the new CPU from Ryzen and Linux preinstalled.
-
XZ Gets the All-Clear
The back door xz vulnerability has been officially reverted for Fedora 40 and versions 38 and 39 were never affected.
-
Canonical Collaborates with Qualcomm on New Venture
This new joint effort is geared toward bringing Ubuntu and Ubuntu Core to Qualcomm-powered devices.
-
Kodi 21.0 Open-Source Entertainment Hub Released
After a year of development, the award-winning Kodi cross-platform, media center software is now available with many new additions and improvements.
-
Linux Usage Increases in Two Key Areas
If market share is your thing, you'll be happy to know that Linux is on the rise in two areas that, if they keep climbing, could have serious meaning for Linux's future.
-
Vulnerability Discovered in xz Libraries
An urgent alert for Fedora 40 has been posted and users should pay attention.
-
Canonical Bumps LTS Support to 12 years
If you're worried that your Ubuntu LTS release won't be supported long enough to last, Canonical has a surprise for you in the form of 12 years of security coverage.
-
Fedora 40 Beta Released Soon
With the official release of Fedora 40 coming in April, it's almost time to download the beta and see what's new.
-
New Pentesting Distribution to Compete with Kali Linux
SnoopGod is now available for your testing needs