Data commit

Task/Take-notes-on-the-command-line/Go/take-notes-on-the-command-line.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"strings"
+	"time"
+)
+
+func addNote(fn string, note string) error {
+	f, err := os.OpenFile(fn, os.O_RDWR|os.O_APPEND|os.O_CREATE, 0666)
+	if err != nil {
+		return err
+	}
+	_, err = fmt.Fprint(f, time.Now().Format(time.RFC1123), "\n\t", note, "\n")
+	// To be extra careful with errors from Close():
+	if cErr := f.Close(); err == nil {
+		err = cErr
+	}
+	return err
+}
+
+func showNotes(w io.Writer, fn string) error {
+	f, err := os.Open(fn)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil // don't report "no such file"
+		}
+		return err
+	}
+	_, err = io.Copy(w, f)
+	f.Close()
+	return err
+}
+
+func main() {
+	const fn = "NOTES.TXT"
+	var err error
+	if len(os.Args) > 1 {
+		err = addNote(fn, strings.Join(os.Args[1:], " "))
+	} else {
+		err = showNotes(os.Stdout, fn)
+	}
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}