Home » Golang » Golang Programs

Golang program to add program filename in log message as a prefix using log.SetFlags() function

Here, we are going to learn how to add program filename in log message as a prefix using log.SetFlags() function in Golang (Go Language)?
Submitted by Nidhi, on April 23, 2021 [Last updated : March 05, 2023]

How to add program filename in log message as a prefix in Golang?

Problem Solution:

Here, we will use log.SetFlags() function to add program filename in log message as a prefix. Here, we will pass log.Lshortfile constant in log.SetFlags() function.

Program/Source Code:

The source code to add program filename in log message as a prefix using log.SetFlags() function is given below. The given program is compiled and executed on the ubuntu 18.04 operating system successfully.

Golang code to add program filename in log message as a prefix using log.SetFlags() function

// Golang program to add program filename
// as a prefix in the log message

package main

import "log"
import "fmt"

func main() {

	//program filename as a prefix
	log.SetFlags(log.Lshortfile)

	log.Println("Log Line1")
	log.Println("Log Line2")

	fmt.Println("Program finished")
}

Output:

$ go run hello.go 
hello.go:14: Log Line1
hello.go:15: Log Line2
Program finished

Explanation:

In the above program, we declare the package main. The main package is used to tell the Go language compiler that the package must be compiled and produced the executable file. Here, we imported the "fmt" package to use the Println() function and we also imported the "log" package to use the log functions.

In the main() function, we added program filename as a prefix in every line of log message using log. Lshortfile constant in logSetFlags() function.

Golang log Package Programs »

---