cmd: convert from fmt to log package

cmd/yatwiki-server/main.go

@@ -3,8 +3,8 @@ package main
 import (
 	"encoding/json"
 	"flag"
-	"fmt"
 	"io/ioutil"
+	"log"
 	"net/http"
 	"os"
 
@@ -27,34 +27,30 @@ func main() {
 			if cfg, err := json.MarshalIndent(opts, "", "\t"); err == nil {
 				err := ioutil.WriteFile(*configPath, cfg, 0644)
 				if err != nil {
-					fmt.Fprintf(os.Stderr, "Failed to save default configuration file: %s", err.Error())
+					log.Printf("Failed to save default configuration file: %s", err.Error())
 				}
 			}
 		} else {
-			fmt.Fprintf(os.Stderr, "Failed to load configuration file '%s': %s\n", *configPath, err.Error())
+			log.Fatalf("Failed to load configuration file '%s': %s\n", *configPath, err.Error())
-			os.Exit(1)
 		}
 	} else {
-		fmt.Printf("Loading configuration from '%s'...\n", *configPath)
+		log.Printf("Loading configuration from '%s'...\n", *configPath)
 		err = json.Unmarshal(cfg, &opts)
 		if err != nil {
-			fmt.Fprintf(os.Stderr, "Failed to parse configuration file: %s\n", err.Error())
+			log.Fatalf("Failed to parse configuration file: %s\n", err.Error())
-			os.Exit(1)
 		}
 	}
 
 	ws, err := yatwiki.NewWikiServer(&opts)
 	if err != nil {
-		fmt.Fprintln(os.Stderr, err.Error())
+		log.Fatalln(err.Error())
-		os.Exit(1)
 	}
 	defer ws.Close()
 
-	fmt.Printf("YATWiki now listening on %s\n", *bindAddr)
+	log.Printf("YATWiki now listening on %s\n", *bindAddr)
 	err = http.ListenAndServe(*bindAddr, ws)
 	if err != nil {
-		fmt.Fprintln(os.Stderr, err.Error())
+		log.Fatalln(err.Error())
-		os.Exit(1)
 	}
 
 	os.Exit(0)