Question: I have this log file that I check on a frequent basis and because of the format of it, it's quite easier to read when pretty printed. I'd like to do so in a tail.

Logs in the file like:

```
2019-07-04T09:53:04-07:00   some.package.placeholder.stderr {"log": "The content", "foo": "bar", "baz": "blah"}
2019-07-04T10:15:37-07:00   some.package.placeholder.stderr {"log": "I'm actually", "foo": "bar", "baz": "blah"}
2019-07-04T10:15:37-07:00   some.package.placeholder.stderr {"log": "Interested on", "foo": "bar", "baz": "blah"}

```

And I want to do something similar to

```
tail -f myLogFile | grep [...?...] | jq '.log'

```

So when tailing I get:

```
The content
I'm actually
Interested on

```

Or even:

```
2019-07-04T09:53:04-07:00   The content
2019-07-04T10:15:37-07:00   I'm actually
2019-07-04T10:15:37-07:00   Interested on

```

Answer: 
With GNU grep for `-o`:

```
$ tail file | grep -o '{[^}]*}' | jq -r '.log'
The content
I'm actually
Interested on

```

With any awk:

```
$ tail file | awk 'sub(/.*{/,"{")' | jq -r '.log'
The content
I'm actually
Interested on

$ tail file | awk '{d=$1} sub(/.*{/,""){$0="{\"date\": \""d"\", " $0} 1' | jq -r '.date + " " + .log'
2019-07-04T09:53:04-07:00 The content
2019-07-04T10:15:37-07:00 I'm actually
2019-07-04T10:15:37-07:00 Interested on

```

That last one works by merging the date field from the input into the json so then jq can just select and print it with the log field.
If the log lines are tab delimited, you can read the lines in raw and split on tabs. Which you could then parse the json and filter to your hearts content, and recombine as necessary.

```
$ tail -f myLogFile | jq -Rr 'split("\t") | [.[0], (.[2] | fromjson.log)] | join("\t")'
2019-07-04T09:53:04-07:00   The content
2019-07-04T10:15:37-07:00   I'm actually
2019-07-04T10:15:37-07:00   Interested on

```