jq · lesson 5 of 32 · Pipes & building output

Pipes

| feeds each output of the filter on its left into the filter on its right. It is how small filters combine into a program.

Example 1Names, upper-cased

Document

{
  "team": "Platform",
  "office": { "city": "Berlin", "floor": 3 },
  "members": [
    { "name": "Ada", "age": 36, "role": "lead", "active": true,
      "email": "[email protected]", "skills": ["rust", "sql"] },
    { "name": "Linus", "age": 28, "role": "dev", "active": true,
      "email": null, "skills": ["c", "shell"] },
    { "name": "Grace", "age": 45, "role": "dev", "active": false,
      "skills": ["cobol"] },
    { "name": "Alan", "age": 41, "role": "qa", "active": true,
      "email": "[email protected]", "skills": [] }
  ]
}

Query

.members[] | .name | ascii_upcase

.members[] Produces four outputs, one per member.
| .name Each output flows into the next filter, which reads name…
| ascii_upcase …and on into the next, which upper-cases the string.

Result

"ADA"
"LINUS"
"GRACE"
"ALAN"

Try it in the playground

Good to know

Read a pipeline left to right: | hands every output of its left side, one at a time, to its right side.
.a.b[0] and .a | .b | .[0] mean exactly the same thing.