Bugfix when no input file specified

This reverts commit 74ad307bd1.

.gitignore

@@ -1,2 +1,3 @@
 ./20211228134923.20211228151348
 tmpwrk
+godit

main.go

@@ -33,7 +33,7 @@ import (
 )
 
 const (
-	version = "5.9.9c"
+	version = "0.6.1"
 )
 
 var (
@@ -51,11 +51,11 @@ func main() {
 	var syslog23 bool
 	var json bool
 
-	pflag.BoolVarP(&oneLine, "oneline", "l", false, "Prints the entire record on the same line.")
+	pflag.BoolVarP(&oneLine, "oneline", "l", false, "Prints the entire record on the same line")
-	pflag.BoolVarP(&noUserResolve, "numeric", "n", false, "Do not convert user and group IDs to their names but leave in their numeric forms.")
+	pflag.BoolVarP(&noUserResolve, "numeric", "n", false, "Do not convert user and group IDs to their names but leave in their numeric forms")
 	pflag.BoolVarP(&json, "json", "j", false, "Print compact json")
-	pflag.BoolVarP(&syslog23, "syslog23", "s", false, "Print time as \"2006-01-02T15:04:05.000Z07:00\", RFC339 with ms, also used on RSYSLOG_SyslogProtocol23Format. \"msec\" field will not be print in json output.")
+	pflag.BoolVarP(&syslog23, "syslog23", "s", false, "Print time as \"2006-01-02T15:04:05.000Z07:00\", RFC339 with ms, also used on RSYSLOG_SyslogProtocol23Format. \"msec\" field will not be print in json output")
-	pflag.BoolVarP(&showVersion, "version", "V", false, "Show version then exit")
+	pflag.BoolVarP(&showVersion, "version", "V", false, "Show version and exit")
 
 	var Usage = func() {
 		fmt.Fprintf(os.Stderr, "Usage of \"%s [opts] auditfile\":\n", os.Args[0])
@@ -84,6 +84,10 @@ func main() {
 	}
 
 	args := os.Args
+	if len(os.Args) < 2 {
+		pflag.Usage()
+		os.Exit(1)
+	}
 	filename := args[len(args)-1]
 
 	var f *os.File