This recipe demonstrates how to use flag to build a command line program, how to convert string slice to string and how to write sentence to file specified by user.
Usage example: writefile -f test.txt hi this is a test.
package main
import (
"flag"
"io"
"log"
"os"
"strings"
)
func convertSliceToString(s []string) string {
// Convert string slice to string
return strings.Join(s, " ")
}
func writeFile(f, txt string) error {
file, e := os.OpenFile(f, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
if e != nil {
return e
}
defer file.Close()
_, wrErr := io.WriteString(file, txt)
if wrErr != nil {
return wrErr
}
file.Sync()
return nil
}
func main() {
filename := flag.String("f", "", "specify file name")
flag.Parse()
// flag.Args() returns string slice.
txt := convertSliceToString(flag.Args())
e := writeFile(*filename, txt)
if e != nil {
log.Fatal(e)
}
}
cyruslab 