Add quiet mode

When -quiet is specified on the command line we will only show issues
when issues were found.

Fixes #55

main.go

@@ -38,8 +38,12 @@ var flagFormat = flag.String("fmt", "text", "Set output format. Valid options ar
 // output file
 var flagOutput = flag.String("out", "", "Set output file for results")
 
+// config file
 var flagConfig = flag.String("conf", "", "Path to optional config file")
 
+// quiet
+var flagQuiet = flag.Bool("quiet", false, "Only show output when errors are found")
+
 var usageText = `
 GAS - Go AST Scanner
 
@@ -216,6 +220,12 @@ func main() {
 		}
 	}
 
+	issuesFound := len(analyzer.Issues) > 0
+	// Exit quietly if nothing was found
+	if !issuesFound && *flagQuiet {
+		os.Exit(0)
+	}
+
 	// Create output report
 	if *flagOutput != "" {
 		outfile, err := os.Create(*flagOutput)
@@ -229,7 +239,7 @@ func main() {
 	}
 
 	// Do we have an issue? If so exit 1
-	if len(analyzer.Issues) > 0 {
+	if issuesFound {
 		os.Exit(1)
 	}
 }