Ignore Unparseable JSON with jq

Assuming that each log entry is exactly one line, you can use the -R or --raw-input option to tell jq to leave the lines unparsed, after which you can prepend fromjson? | to your filter to make jq try to parse each line as JSON and throw away the ones that error.

I have log stream where some messages are in json format.I want to pipe the json messages through jq, and just echo the rest.

The json messages are on a single line.

Solution: use grep and tee to split the lines in two streams, those starting with "^{" pipe through jq and the rest just echo to terminal.

kubectl logs -f web-svjkn | tee >(grep -v "^{") | grep "^{" | jq .

or

cat logs | tee >(grep -v "^{") | grep "^{" | jq .

Explanation:tee generates 2nd stream, and grep -v prints non json info, 2nd grep only pipes what looks like json opening bracket to jq.

There are several Q&As on the FAQ page dealing with the topic of "invalid JSON", but see in particular the Q:

Is there a way to have jq keep going after it hits an error in the input file?

In particular, this shows how to use --seq.

However, from the the sparse details you've given (SO recommends a minimal example be given), it would seem it might be better simply to use inputs. The idea is to process one JSON entity at a time, using "try/catch", e.g.

def handle: inputs | [., "length is \(length)"] ;def process: try handle catch ("Failed", process) ;process  

Don't forget to use the -n option when invoking jq.

See also Processing not-quite-valid JSON.