Skip to main content Logo

Quis custodiet ipsos custodes?
Home | About | All pages | Cluster Status | RSS Feed

Get a JSON value with bash and sed

Published: 26-02-2019 | Author: Remy van Elst | Text only version of this article

❗ This post is over five years old. It may no longer be up to date. Opinions may have changed.

Recently I was asked to get one value from a json object using only shell tools. The json in question is from a dutch radio station and it lists the current song that is played. Using this together with a few shell commands and notify- send we can show the current song when it changes as a desktop notification. I'd rather use Python or jq if it has to be shell. In this case the co-worker asked to just use simple shell tools and no external dependencies.

Recently I removed all Google Ads from this site due to their invasive tracking, as well as Google Analytics. Please, if you found this content useful, consider a small donation using any of the options below:

I'm developing an open source monitoring app called Leaf Node Monitoring, for windows, linux & android. Go check it out!

Consider sponsoring me on Github. It means the world to me if you show your appreciation and you'll help pay the server costs.

You can also sponsor me by getting a Digital Ocean VPS. With this referral link you'll get $200 credit for 60 days. Spend $25 after your credit expires and I'll get $25!

This is the json file, formatted:

# curl -s ''
        "PlayingNow":"Joke Buis - Welk Een Vriend Is Onze Jezus",

The field we want is the PlayingNow field. Using sed, a regular expression with a backreference (\1) it can be shown:

sed -n 's|.*"PlayingNow":"\([^"]*\)".*|\1|p'

Example output:

curl -s '' | sed -n 's|.*"PlayingNow":"\([^"]*\)".*|\1|p'

Joke Buis - Welk Een Vriend Is Onze Jezus

The full script to send the desktop notifications:

if [[ ! -f /tmp/gnr-prev.txt ]]; then touch /tmp/gnr-prev.txt; fi
PREVSONG="$(cat /tmp/gnr-prev.txt)"
curl -s '' | sed -n 's|.*"PlayingNow":"\([^"]*\)".*|\1|p' > /tmp/gnr-cur.txt
CURSONG="$(cat /tmp/gnr-cur.txt)"
if [[ "$PREVSONG" != "$CURSONG" ]]; then
    mv /tmp/gnr-prev.txt /tmp/gnr.$(date +%s).txt;
    mv /tmp/gnr-cur.txt /tmp/gnr-prev.txt;
    notify-send "GNR: $CURSONG";

Put it in cron for regular execution. Add this to your crontab as well if you use KDE:


Replace remy with your username.

Tags: bash , bash-bits , curl , json , python , sed , shell , snippets