Zgo - custom_log.go

package main

import (
    "fmt"
    "io"
    "log"
    "os"
    "path"
)

func main() {
    flag := os.O_APPEND | os.O_CREATE | os.O_WRONLY

    logFile := path.Join(os.TempDir(), "mGo.log")
    fmt.Println(logFile)

    f, err := os.OpenFile(logFile, flag, 0644)
    // The call to os.OpenFile() creates the log file for writing, 
    // if it does not already exist, or opens it for writing by appending 
    // new data at the end of it.
    if err != nil {
        fmt.Println(err)
        return
    }
    defer f.Close()

    lFlags := log.Ldate | log.Lshortfile
    infoLogger := log.New(f, "INFO: ", lFlags)
    infoLogger.Println("Hello there!")
    infoLogger.SetFlags(log.Lshortfile | log.LstdFlags)
    infoLogger.Println("Another log entry!")

    file, err := os.OpenFile("mylog.log", flag, 0644)
    if err != nil {
        fmt.Println(err)
        os.Exit(0)
    }
    defer file.Close()

    w := io.MultiWriter(file, os.Stderr)
    mLogger := log.New(w, "myApp: ", log.LstdFlags)
    mLogger.Printf("BOOK %d", os.Getpid())
}