To parse JSON in shell scripts using jq, you can utilize its filtering syntax to extract values from structured data. Start by piping JSON input into jq or specifying a file, such as echo '{"name": "Alice"}' | jq '.name' or jq '.name' data.json, which extracts the value of the "name" key. For nested objects like { "user": { "details": { "name": "Bob" } }}, use dot notation: jq '.user.details.name' data.json. When handling arrays, such as { "users": [ {"name": "Alice"}, {"name": "Bob"} ] }, retrieve all names with jq '.users[].name' data.json, or access a specific element via index: jq '.users[0].name' data.json. To process results further in a script, use the -r flag for raw output and combine fields using string interpolation: jq -r '"Name: $(.user.details.name), Email: $(.user.details.email)"' data.json. With these methods, jq simplifies JSON parsing and manipulation within shell environments.
Parsing JSON in a shell script isn’t straightforward by default, but with jq, it becomes both easy and powerful. The key is knowing how to structure your command so that you extract exactly what you need from the JSON data.
Basic Syntax for Using jq
The basic way to use jq is to pipe JSON data into it or specify a file. Here’s the general form:
jq '[filter]' [file]
Or if you're piping data:
echo '{"name": "Alice"}' | jq '.name'This will output:
"Alice"
You can see that .name is the filter here — it tells jq which field to extract.
If you're working with a JSON file (data.json), you'd do something like:
jq '.name' data.json
Extracting Values from Nested Objects
JSON often contains nested structures. Let's say you have this kind of data:
{
"user": {
"id": 123,
"details": {
"name": "Bob",
"email": "bob@example.com"
}
}
}To get the name, you’d chain keys together:
jq '.user.details.name' data.json
And that would return:
"Bob"
You don't need to write special parsing code — just build the right path using dot notation.
Handling Arrays in JSON
A common case is when a value is inside an array. For example:
{
"users": [
{"name": "Alice"},
{"name": "Bob"}
]
}To get all names:
jq '.users[].name' data.json
That outputs:
"Alice" "Bob"
If you want just the first name:
jq '.users[0].name' data.json
Which gives:
"Alice"
You can also loop over them in a script:
jq -r '.users[].name' data.json | while read name; do echo "User: $name" done
-rtellsjqto output raw strings (without quotes).
Formatting Output for Use in Scripts
Sometimes you want clean values without quotes or extra formatting. That’s where the -r flag comes in handy.
For example:
jq -r '.user.details.name' data.json
Returns:
Bob
Without the quotes — which makes it easier to assign to variables or process further in shell scripts.
Also, if you're combining multiple fields, you can format them using string interpolation:
jq -r '"Name: \(.user.details.name), Email: \(.user.details.email)"' data.json
Output:
Name: Bob, Email: bob@example.com
This makes it simple to generate log lines or messages directly from JSON.
So, basically, once you understand how to navigate the structure with filters, jq becomes a reliable tool for handling JSON in shell scripts. It's not complicated, but getting the syntax right helps avoid frustration later.
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