Conditionally pass to jq if the line looks a bit like jason

filtered_to_jq.sh

#!/bin/zsh

# Conditionally pass line or file data to jq.
#
# First argument is a filter override to jq, default is '.'
# Second argument is a file, otherwise stdin is used

JQ_FILTER=${1:-'.'}

while read line
do
  FIRST=${line:0:1}
  LAST=${line: -1}

  if [[ "$FIRST" = "{" && "$LAST" = "}" ]]; then
    echo "$line" | jq -cC $JQ_FILTER
  fi
done < "${2:-/dev/stdin}"

I guess it would be more unixy if this was just is_json

cat messy-json.txt | is_json | jq -cC '.'

and I could alias that is_json | jq combo

is_json.sh would just be

#!/bin/zsh

# Filter by line if it looks like json 
#
# First argument is a file, otherwise stdin is used

while read line
do
  FIRST=${line:0:1}
  LAST=${line: -1}

  if [[ "$FIRST" = "{" && "$LAST" = "}" ]]; then
    echo "$line"
  fi
done < "${1:-/dev/stdin}"

And if you alias fjq="is_json | jq" you can do cat messy-data.txt | fjq '.name'

Perhaps a grep regex could work better? Could essentially be a .trim() as well

cat messy.txt | grep -E '^\b{.*}' | jq -Cc '.'

K that's my alias now, I like it.

# filtered to jq
alias fjq="grep -E '^\b{.*}' | jq"

#...
# Usage
cat messy.log | fjq -cC '.name'