Go: Read a file line by line

file, err := os.Open("file.txt")
if err != nil {
    log.Fatal(err)
}
defer file.Close()

scanner := bufio.NewScanner(file)
for scanner.Scan() {
    fmt.Println(scanner.Text())
}

if err := scanner.Err(); err != nil {
    log.Fatal(err)
}

For more advanced scanning, see the examples in the bufio.Scanner documentation.