Do not overwrite user config on login

nethack-launcher/create_user_files.go

@@ -11,10 +11,12 @@ func createUserFiles(username string) {
 	userPath := fmt.Sprintf("%s/user/%s/ttyrec/", config.NethackLauncher.HackDir, username)
 	exec.Command("mkdir", "-p", userPath).Run()
 
-	// copy in rc file
+	// copy in rc file if it does not exist
 	hackRCLoc := fmt.Sprintf("%s/.nethackrc", config.NethackLauncher.HackDir)
-	hackRCDest := fmt.Sprintf("%s/user/%s/.nethackrc", config.NethackLauncher.HackDir, username)
-	exec.Command("cp", hackRCLoc, hackRCDest).Run()
+	if _, err := os.Stat(hackRCLoc); os.IsNotExist(err) {
+		hackRCDest := fmt.Sprintf("%s/user/%s/.nethackrc", config.NethackLauncher.HackDir, username)
+		exec.Command("cp", hackRCLoc, hackRCDest).Run()
+	}
 
 	// create necessary directories if they dont exist
 	userpath := fmt.Sprintf("%s/user/%s", config.NethackLauncher.HackDir, username)