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
-
New Slimbook EVO with Raw AMD Ryzen Power
If you're looking for serious power in a 14" ultrabook that is powered by Linux, Slimbook has just the thing for you.
-
The Gnome Foundation Struggling to Stay Afloat
The foundation behind the Gnome desktop environment is having to go through some serious belt-tightening due to continued financial problems.
-
Thousands of Linux Servers Infected with Stealth Malware Since 2021
Perfctl is capable of remaining undetected, which makes it dangerous and hard to mitigate.
-
Halcyon Creates Anti-Ransomware Protection for Linux
As more Linux systems are targeted by ransomware, Halcyon is stepping up its protection.
-
Valve and Arch Linux Announce Collaboration
Valve and Arch have come together for two projects that will have a serious impact on the Linux distribution.
-
Hacker Successfully Runs Linux on a CPU from the Early ‘70s
From the office of "Look what I can do," Dmitry Grinberg was able to get Linux running on a processor that was created in 1971.
-
OSI and LPI Form Strategic Alliance
With a goal of strengthening Linux and open source communities, this new alliance aims to nurture the growth of more highly skilled professionals.
-
Fedora 41 Beta Available with Some Interesting Additions
If you're a Fedora fan, you'll be excited to hear the beta version of the latest release is now available for testing and includes plenty of updates.
-
AlmaLinux Unveils New Hardware Certification Process
The AlmaLinux Hardware Certification Program run by the Certification Special Interest Group (SIG) aims to ensure seamless compatibility between AlmaLinux and a wide range of hardware configurations.
-
Wind River Introduces eLxr Pro Linux Solution
eLxr Pro offers an end-to-end Linux solution backed by expert commercial support.