How to extract value from json contained in a variable using jq in bash

Question

I am writing a bash script which has a json value stored in a variable now i want to extract the values in that json using Jq. The code used is.

json_val={"code":"lyz1To6ZTWClDHSiaeXyxg","redirect_to":"http://example.com/client-redirect-uri?code=lyz1To6ZTWClDHSiaeXyxg"}
  code_val= echo"$json_val" | jq '.code'

This throws an error of no such file or direcotry.

If i change this to

json_val={"code":"lyz1To6ZTWClDHSiaeXyxg","redirect_to":"http://example.com/client-redirect-uri?code=lyz1To6ZTWClDHSiaeXyxg"}
  code_val=echo" $json_val " | jq '.code'

This does not throws any error but the value in code_val is null.

If try to do it manually echo {"code":"lyz1To6ZTWClDHSiaeXyxg","redirect_to":"http://example.com/client-redirect-uri?code=lyz1To6ZTWClDHSiaeXyxg"} | jq '.code' it throws parse numeric letter error.

how can i do it in first case.

Answer 1

You may use this:

json_val='{"code":"lyz1To6ZTWClDHSiaeXyxg","redirect_to":"http://example.com/client-redirect-uri?code=lyz1To6ZTWClDHSiaeXyxg"}'
code_val=$(jq -r '.code' <<< "$json_val")
echo "$code_val"

lyz1To6ZTWClDHSiaeXyxg

Note following changes:

• Wrap complete json string in single quotes
• use of $(...) for command substitution
• Use of <<< (here-string) to avoid a sub-shell creation

PS: If you're getting json text from a curl command and want to store multiple fields in shell variables then use:

read -r code_val redirect_to < <(curl ... | jq -r '.code + "\t" + .redirect_to')

Where ... is your curl command.