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golangHow to write log to file


package main
import ( "log"; "os" )

func main() {
  f, err := os.OpenFile("/tmp/log.log", os.O_RDWR | os.O_CREATE | os.O_APPEND, 0666)
  if err != nil {
    log.Fatalf("Can't open log file", err)
  }
  defer f.Close()
  
  log.SetOutput(f)
  
  log.Println("something to log")
}ctrl + c
package main

default package declaration

func main() {

declare main function that will be launched automatically

os.OpenFile

opens file handler

log.SetOutput(

will write logs to specified file handler

log.Println(

log sample message (will be logged to file)


Usage example

package main
import ( "log"; "os" )

func main() {
  f, err := os.OpenFile("/tmp/log.log", os.O_RDWR | os.O_CREATE | os.O_APPEND, 0666)
  if err != nil {
    log.Fatalf("Can't open log file", err)
  }
  defer f.Close()

  log.SetOutput(f)

  log.Println("something to log")
}
output
~# cat /tmp/log.log 
2022/07/21 11:19:43 something to log