How to handle and log errors with the log package in Go?

To handle and log errors with the log package in Go, you can follow these steps:

Import the log package:

import "log"

Set the output to a file or standard output:

log.SetOutput(os.Stdout) // set output to standard output
// OR
file, err := os.OpenFile("logfile.log", os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
if err != nil {
    log.Fatal(err)
}
defer file.Close()
log.SetOutput(file) // set output to a file

Set the log prefix and flags:

log.SetPrefix("ERROR: ")
log.SetFlags(log.LstdFlags | log.Lmicroseconds) // Use desired flags

Handle and log errors:

err := SomeFunction()
if err != nil {
    log.Printf("Error occurred: %v", err)
    // or
    log.Fatal("Fatal error occurred: ", err)
    // or
    log.Panic("Panic occurred: ", err)
}

You can choose one of the following log functions based on your requirements:

log.Print(v ...interface{}) or log.Println(v ...interface{})
- Prints the log message with the provided values.
log.Printf(format string, v ...interface{})
- Formats and prints the log message.
log.Fatal(v ...interface{}) or log.Fatalln(v ...interface{})
- Prints the log message with the provided values and exits the program with a non-zero status code.
log.Fatalf(format string, v ...interface{})
- Formats and prints the log message, then exits the program with a non-zero status code.
log.Panic(v ...interface{}) or log.Panicln(v ...interface{})
- Prints the log message with the provided values and causes a panic.
log.Panicf(format string, v ...interface{})
- Formats and prints the log message, then causes a panic.

With these steps, you can handle and log errors using the log package in Go.