jq: CLI JSON processor

Parse object:

json='{
  "name": "Alice",
  "age": 30,
  "city": "New York"
}'

name=$(echo "$json" | jq -r '.name')
age=$(echo "$json" | jq -r '.age')
city=$(echo "$json" | jq -r '.city')

echo "$name is $age years old and lives in $city"
# Alice is 30 years old and lives in New York

jq can directly read from file:

cat > data.json << EOF
{
  "name": "Alice",
  "age": 30,
  "city": "New York"
}
EOF

name=$(jq '.name' data.json)
age=$(jq '.age' data.json)
city=$(jq '.city' data.json)

echo "$name is $age years old and lives in $city"
rm data.json

Or read from API endpoint:

name=$( curl -s https://api.github.com/users/pranabdas | jq -r '.name' )
location=$( curl -s https://api.github.com/users/pranabdas | jq -r '.location' )
echo "$name is from $location."
# Pranab Das is from Singapore.

Iterate over an array of items:

cat > data.json << EOF
[
  {
    "name": "Alice",
    "age": 30
  },
  {
    "name": "Bob",
    "age": 35
  }
]
EOF

jq -c '.[]' data.json | while read -r item; do
  name=$(echo "$item" | jq -r '.name')
  age=$(echo "$item" | jq -r '.age')
  echo "Name: $name, Age: $age"
done
rm data.json

In case of arbitrary keys in an object:

json='{
  "name": "Alice",
  "age": 30,
  "city": "New York"
}'

echo "$json" | jq -r 'to_entries[] | "\(.key)=\(.value)"' | while IFS='=' read -r key value; do
  echo "key: $key, value: $value"
done

Update an json object:

cat > data.json << EOF
{
  "name": "Alice",
  "age": 30
}
EOF

jq '.age = 32' data.json > tmp.json
mv tmp.json data.json
cat data.json
rm data.json

Update an array of objects based key match:

cat > data.json << EOF
[
  {
    "name": "Alice",
    "age": 30
  },
  {
    "name": "Bob",
    "age": 35
  }
]
EOF

jq --arg name "Alice" --arg age 31 'map(if .name == $name then .age = $age else . end)' data.json > tmp.json
mv tmp.json data.json
cat data.json
rm data.json

Select item based on key:

cat > data.json << EOF
[
  { "id": 1, "status": "pending" },
  { "id": 2, "status": "pending" },
  { "id": 3, "status": "pending" }
]
EOF

jq '.[] | select(.id == 2) | .status = "completed"' data.json
rm data.json

Pretty print/format json using jq:

cat > data.json << EOF
[{
    "name": "Alice", "age": 30
  },
  {
     "name": "Bob",
"age": 35}
]
EOF

cat data.json | jq '.' > tmp.json
mv tmp.json data.json
cat data.json
rm data.json

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