Logging library for bash to configure the current script to log to console and a file with timestamp and log level

logging.sh

# Reads from stdin and prefixes each line with a timestamp (if true) and default log level (if missing)
prefix_log() { local default_level=$1
    while read -r line; do
        local timestamp=''
        local level=''
        if ! [[ $line =~ ^[0-9]{4}-[0-9]{2}-[0-9]{2} ]]; then
            timestamp="$(date +"%Y-%m-%d %T.%3N") - "
            if ! [[ $line =~ ^(TRACE|DEBUG|INFO|WARN|ERROR) ]]; then
                level="$default_level - "
            fi
        fi
        echo "$timestamp$level$line"
    done
}

# Sets up script to prefix every line with timestamp and log level and send stdout and stderr to a file
# - use_xtrace: If 'true', log every line of code as it is executed
# - stderr_to_stdout: If 'true', redirect stderr to stdout
configure_logging() { local path=$1; local stderr_to_stdout=$2; local use_xtrace=$3
    mkdir -p "$(basename "$path")"
    exec 3>> "$path"
    exec > >(prefix_log INFO | tee -i >(cat >&3))
    if [[ $stderr_to_stdout == true ]]; then
        exec 2> >(prefix_log ERROR)
    else
        exec 2> >(prefix_log ERROR | tee -i >(cat >&3) >&2)
    fi
    PS4=' TRACE - $(basename $BASH_SOURCE):$LINENO.$BASH_SUBSHELL${FUNCNAME[0]:+ [${FUNCNAME[0]}]} + '
    if [[ $use_xtrace == true ]]; then
        set -x
    fi
}