Non-greedy regex extraction from JSON with sed

Question

Some JSON:

{"theSecret":"flhiusdh4543sdfasf34sdf+fsfs/sdf43454=","foo":{"bar":41,"something":"hello world","else":"hi","date":20230101,"qux":0,"digest":"sfhusdf234jkkjuiui23kjkj/SFDF34SDSFDS="}}

Prettified:

{
  "theSecret": "flhiusdh4543sdfasf34sdf+fsfs/sdf43454=",
  "foo": {
    "bar": 41,
    "something": "hello world",
    "else": "hi",
    "date": 20230101,
    "qux": 0,
    "digest": "sfhusdf234jkkjuiui23kjkj/SFDF34SDSFDS="
  }
}

I want the value of the theSecret key.

I tried this:

$ echo "$json" | sed -nE 's/.*theSecret":"(.*)".*/\1/p'    # (.*?) doesn't work

Which gives:

flhiusdh4543................4SDSFDS=

i.e. from theSecret until the end of digest. That's because sed lacks non-greedy quantifiers, so .*? doesn't work.

How can I do this?

(This is in an alpine container, which has sed, grep and awk. jq and perl are unavailable.)

Answer 1

Instead of using a non-greedy quantifier, use a pattern that doesn't match the terminating ".

$ echo "$json" | sed -nE 's/.*theSecret":"([^"]*)".*/\1/p'    # (.*?) doesn't work