v0.2: Read stdin if filename is empty or "-"

main.go

@@ -17,27 +17,43 @@ import (
 )
 
 var (
-	gVersion = "0.0.1"
+	gVersion = "0.2"
+
+	Usage = func() {
+		fmt.Printf("deldify v%s\n", gVersion)
+		fmt.Printf("Usage: deldify [-h|--help] [filename]\n")
+		fmt.Printf("       read stdin if filename is empty or '-'\n")
+		fmt.Printf("Flags:\n")
+		fmt.Printf("       -h|--help: Display help\n")
+		os.Exit(1)
+	}
 )
 
+
 func main() {
 	var input string
 
-	flag.Parse()
-	if len(flag.Args()) < 1 {
-		fmt.Printf("deldify v%s\n", gVersion)
-		fmt.Printf("Usage: deldify filename\n")
-		os.Exit(1)
-	}
-	input = flag.Args()[0]
+	flag.Usage = Usage
 
-	// open file
+	flag.Parse()
+
+	if len(flag.Args()) > 0 {
+		input = "-"
+	}
+
+	// open file or stdin
+	var f *os.File
+
+	if !strings.EqualFold(input, "-") {
 		f, err := os.Open(input)
 		if err != nil {
 			fmt.Errorf("%v\n", err)
 		}
 		// remember to close the file at the end of the program
 		defer f.Close()
+	} else {
+		f = os.Stdin
+	}
 
 	// read the file line by line using scanner
 	scanner := bufio.NewScanner(f)