Merging Two JSON Files in Linux

You can quickly merge multiple JSON files in Linux using fx with cat and --slurp.

Basic Merge

If all your JSON files contain flat objects (no nesting), you can do:

cat a.json b.json | fx --slurp 'Object.assign({}, ...x)'

This reads all files, combines them into one array (x), and merges them into a single object. Later values override earlier ones.

Example

a.json

{
  "name": "Alice",
  "age": 30
}

b.json

{
  "age": 35,
  "city": "Berlin"
}

Result

{
  "name": "Alice",
  "age": 35,
  "city": "Berlin"
}

Merging All JSON Files in a Directory

cat *.json | fx --slurp 'Object.assign({}, ...x)'

This reads all JSON files in the current directory, combines them into one array (x), and merges them into a single object. Later values override earlier ones.