tlog 
Package tlog provides simple APIs to write log to console and file simultaneously.
Tlog is a wrapper around golang's standard log package.
Features:
- Predefined log levels, from debug to critical.
- Console and logfile loglevel can be set separately.
- Console log writes to stderr or stdout according to log level.
Log levels:
- DEBUG - 1
- INFO - 2
- WARN - 3
- ERROR - 4
- CRITICAL - 5
- OFF - 6
Usage
package main
import (
"log"
"github.com/txchen/tlog"
)
func main() {
// By default, only log to console
tlog.WARN.Println("warn")
// Default console loglevel is WARN, we can change it
tlog.SetConsoleLogLevel(tlog.LevelInfo)
tlog.INFO.Println("now I can show")
// Set logfile to enable file based logging
tlog.SetLogFile("z.log")
tlog.CRITICAL.Printf("2 + 2 = %d", 4)
// By default, logfile loglevel is INFO, let's change it
tlog.SetLogfileLogLevel(tlog.LevelDebug)
tlog.Debug.Println("you can only see me in file")
// By default, tlog use Ldate | Ltime flag, you can tune it
tlog.SetLogFlags(log.Ldate | log.Ltime | log.Lshortfile)
// Now you can see different logging style
tlog.ERROR.Println("different style")
// And you can turn off the flag
tlog.SetLogFlags(0)
// Now the output will be "WARN: clean"
tlog.WARN.Println("clean")
// To turn off logging, set the level to off
tlog.SetLogfileLogLevel(tlog.LevelOff)
tlog.SetConsoleLogLevel(tlog.LevelOff)
tlog.CRITICAL.Println("no one can see me")
}