How to format ruby logger?

logger = Logger.new('nice.log')logger.formatter = proc do |severity, datetime, progname, msg|   "NICE: #{msg}\n"endlogger.info("I like cheese.")# nice.log:NICE: I like cheese.

If you want to format only the time, you can easily do it with datetime_format and the standard format specification.For example, if you do:

# Set the logger:logger = Logger.new($stdout)logger.level = Logger::DEBUGlogger.datetime_format = "%Y-%m-%d %H:%M:%S"logger.info("This is an info log...")logger.error("This is an error log...")

You will end up with logs such as:

I, [2015-01-20 14:02:29#17329]  INFO -- myProg: This is an info log...E, [2015-01-20 14:02:29#17329] ERROR -- myProg: This is an error log...

If, instead, you want to completely customize your log, you can use logger.formatter.For example, if you do:

# Set the logger:logger = Logger.new($stdout)logger.level = Logger::DEBUGlogger.formatter = proc do |severity, datetime, progname, msg|    date_format = datetime.strftime("%Y-%m-%d %H:%M:%S")    if severity == "INFO" or severity == "WARN"        "[#{date_format}] #{severity}  (#{progname}): #{msg}\n"    else                "[#{date_format}] #{severity} (#{progname}): #{msg}\n"    endendlogger.info("This is an info log...")logger.error("This is an error log...")

You will end up with logs such as:

[2015-01-20 14:48:04] INFO  (myProg): This is an info log...[2015-01-20 14:48:04] ERROR (myProg): This is an error log...