Adding custom script output to i3status json (output_format = i3bar)

myi3status.sh

#!/bin/bash
i3status | {
    read -r first  # read version object
    echo "$first"  # output version object as is
    # read json array stream and collect each element
    jq -c --stream --unbuffered 'fromstream(1|truncate_stream(inputs))' | {
        # start json array
        echo '['
        # read each json object (arrays)
        while read -r line
        do
            new=$(ls ~/Mail/account/Inbox/new | wc -l)
            mail="{\"name\": \"mail\", \"markup\": \"none\", \"full_text\": \"mail: $new\"}"
            # add $mail object in front of array and print
            echo "$line" | jq --unbuffered -c --argjson mail "$mail" '[ $mail ] + .'
            echo ','
        done
        echo ']'
    }
}