jq · lesson 14 of 32 · Transforming

Updating values

Assignment operators produce a modified copy of the input: = sets a value, |= updates it from its old value, += (and -=, *= …) does arithmetic, and del(path) removes.

Example 1Four kinds of change in one pipeline

Document

{ "name": "Ada", "age": 36, "tmp": true }

Query

.age += 1 | .name |= ascii_upcase | .role = "lead" | del(.tmp)

.age += 1 Arithmetic update: add 1 to the existing value.
.name |= ascii_upcase Update in place: the right side receives the old value and returns the new one.
.role = "lead" Set a key — it is created if it didn't exist.
del(.tmp) Remove a key.

Result

{"name":"ADA","age":37,"role":"lead"}

Try it in the playground

Good to know

Your input is never modified: jq builds a changed copy, which is what the result shows.