Thursday, September 1, 2022

[SOLVED] Bash script: How to read values from a JSON file and use them as input

Issue

I am trying to parse values from JSON file that takes the following form (config.json):

[{
  "gain": "90",
  "exposure": "850",
  "whitebalanceR": "120",
  "whitebalanceG": "185",
  "whitebalanceB": "100",
  "Snap": "True"
}
]

I parse each individual string like this (app.sh):

grep -o '"gain": "[^"]*' config.json | grep -o '[^"]*$'
grep -o '"exposure": "[^"]*' config.json | grep -o '[^"]*$'
grep -o '"whitebalanceR": "[^"]*' config.json | grep -o '[^"]*$'
grep -o '"whitebalanceG": "[^"]*' config.json | grep -o '[^"]*$'
grep -o '"whitebalanceB": "[^"]*' config.json | grep -o '[^"]*$'

This will output the value of the string in the terminal I would like to use the value for each string as input to some function like this:

./someFunc -w '${whitebalanceR} ${whitebalanceG} ${whitebalanceG}' -ax6 -s ${exposure} -g ${gain} -i 1 -o -a -6

But it fails to run? What am I doing wrong? and how to actually use the JSON string as input to a function in bash? Much appreciated


Solution

IMHO, use bash is a bad idea for parsing JSON. But, if you have no choice, use jq as Tranbi suggested:

gain=$( jq -r '.[] | .gain' config.json; )
echo $gain

-r option is required to print the value without quotes.

Hope that helps!



Answered By - Emil Viesná
Answer Checked By - Gilberto Lyons (WPSolving Admin)
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