How to pass jq values to a variable in linux bash script

Question

Can someone please help me out?

I am working on a raspberry pi project and i wanted to control my pins from the cloud. I have this bash script that connects to a web service periodically to check this response. {"status":1,"pin":4}

I am using jq and i was able to get the values that i need using

source gpio

foo = $(curl '{webservice_url}')
echo ${foo} | jq '.status'
echo ${foo} | jq '.pin'

---

output : 1 and 4

problem is when i try to pass the value to a variable and use them it doesn't work

i tried:

 foo = $(curl '{webservice_url}')
 status = `${foo} | jq '.status'`
 pin = `${foo} | jq '.pin'`

 echo "$status"
 echo "$pin"

I tried using echo ${status} and still the error says
status: command not found
pin: command not found

also i tried

source gpio
while true; do
   foo = $(curl '{webservice_url}')
   gpio mode "${foo} | jq '.pin'" out
   gpio write "${foo} | jq '.status'" 1 
   sleep 1
done

but its not working.

Thank you in advance

Answer 1

Here is an illustration of how you can achieve what you want using bash and jq:

# foo=$(curl '{webservice_url}')
foo='{"status": "S", "pin": "P"}'
status=$(jq .status <<< ${foo})
pin=$(jq .pin  <<< ${foo})

echo "$status"
echo "$pin"

Since this involves one invocation of jq per variable, it might be worthwhile using an alternative approach. If your bash has readarray (aka mapfile ), then consider:

readarray -t lines <<< $(jq -cr .status,.pin <<< ${foo})
status=${lines[0]}
pin=${lines[1]}

Otherwise:

i=0
while read -r line
do
    i=$((i+1))
    a[$i]="$line"
done < <(jq -cr .status,.pin <<< ${foo})

Using @tsv

Here's a slightly different approach that relies on the fact that literal tabs cannot appear in JSON strings:

IFS=$'\t' read status pin < <(jq -r '[.status,.pin]|@tsv' <<< ${foo})