Setup a version flag for command to print before flag parsing errors. Remove flag.PrintErrors which was redundant for how we log errors from the output. Include more comments on the code

Author: Chris Gilmer

cmd/main.go

@@ -25,6 +25,9 @@ import (
 const maxNumAccessKeys = 2
 const maxMFATokenPromptAttempts = 5
 
+// version is the published version of the utility
+var version string
+
 var validate *validator.Validate
 
 // MFATokenPair holds two MFA tokens for enabling virtual
@@ -41,6 +44,7 @@ type cliOptions struct {
 	IAMUser      string `required:"true" long:"iam-user" description:"The IAM user name"`
 	Role         string `required:"true" long:"role" description:"The user role type"`
 	Output       string `long:"output" default:"json" description:"The AWS CLI output format"`
+	Version      bool   `long:"version" description:"Print the version and exit"`
 }
 
 // User holds information for the AWS user being configured by this script
@@ -485,13 +489,29 @@ func getPartition(region string) (string, error) {
 func main() {
 	// parse command line flags
 	var options cliOptions
-	parser := flags.NewParser(&options, flags.Default)
+	parser := flags.NewParser(&options, flags.HelpFlag|flags.PassDoubleDash)
 
-	_, err := parser.Parse()
-	if err != nil {
-		log.Fatal(err)
+	// Parse the command line flags
+	_, errParse := parser.Parse()
+
+	// Print the version and exit
+	if options.Version {
+		// Disable output not related to version before printing
+		log.SetFlags(0)
+		if len(version) == 0 {
+			log.Println("development")
+		} else {
+			log.Println(version)
+		}
+		os.Exit(0)
+	}
+
+	// Manage parse errors after checking for version
+	if errParse != nil {
+		log.Fatal(errParse)
 	}
 
+	// Validator used to validate input options for MFA
 	validate = validator.New()
 
 	// initialize things