Bash command to Read, Output and Manipulate JSON File

If you want to read and output the text from a JSON file, you can do that in many ways. Let's take a look at some of them.

Option 1: Using cat command

# cat data.json

{
  "city": "New York",
  "forecast": [
    { "date": "2023-08-18", "temp": 78 },
    { "date": "2023-08-19", "temp": 82 },
    { "date": "2023-08-20", "temp": 75 },
    { "date": "2023-08-21", "temp": 70 },
    { "date": "2023-08-22", "temp": 73 }
  ]
}

Option 2: Using head command

If you want to read and display only x number of files from the top of the JSON file.

# head -n 5 data.json
 
{
  "city": "New York",
  "forecast": [
    { "date": "2023-08-18", "temp": 78 },
    { "date": "2023-08-19", "temp": 82 },

Option 3: Using tail command

If you want to read and display only x number of files from the bottom of the JSON file.

# tail -n 5 data.json 

    { "date": "2023-08-20", "temp": 75 },
    { "date": "2023-08-21", "temp": 70 },
    { "date": "2023-08-22", "temp": 73 }
  ]
}

If you want to read and parse or manipulate a JSON file, then you should make use of the jq binary.

Make sure to install jq package

apt install jq

Example: Parsing and Manipulating JSON file

Display the name of the city from the JSON file:

# jq '.city' data.json

"New York"

Display the temp for each day:

# jq '.forecast[].temp' data.json

78
82
75
70
73

Calculate average temp from JSON:

# jq '[.forecast[].temp] | add / length' data.json

75.6

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