diff --git a/datarecord/datarecord.go b/datarecord/datarecord.go
index 0600245..f5a74ba 100644
--- a/datarecord/datarecord.go
+++ b/datarecord/datarecord.go
@@ -88,6 +88,10 @@ func (obj *dataReader) WithDelimiter(delimiter string) *dataReader {
 }
 
 func (obj *dataReader) WithColumnNames(data string) *dataReader {
+	if len(data) == 0 {
+		return obj
+	}
+
 	obj.columns.names = strings.Split(data, ",")
 	for i := range obj.columns.names {
 		obj.columns.names[i] = strings.TrimSpace(obj.columns.names[i])
diff --git a/statecontext/config.go b/statecontext/config.go
index d90c572..af2080e 100644
--- a/statecontext/config.go
+++ b/statecontext/config.go
@@ -10,12 +10,13 @@ import (
 var errEmptyArgumentList = fmt.Errorf("empty argument list")
 
 type Configuration struct {
-	InputFiles []string
-	DateFormat string
-	DateColumn int
-	PivotColumn int
-	Delimiter string
-	ColumnNames string
+	InputFiles              []string
+	OutputFile              string
+	DateFormat              string
+	DateColumn              int
+	PivotColumn             int
+	Delimiter               string
+	ColumnNames             string
 	IsColumnNamesInFirstRow bool
 
 	programName string
@@ -56,6 +57,7 @@ func covertDateFormat(dateFormat string) string {
 func readCommandLineArguments(config *Configuration, args []string) (fs *flag.FlagSet, err error) {
 	fs = flag.NewFlagSet("", flag.ContinueOnError)
 	fs.BoolVar(&config.printUsage, "h", false, "print usage")
+	fs.StringVar(&config.OutputFile, "o", "", "output file name")
 	fs.StringVar(&config.DateFormat, "t", "YYYYMMDDHHmmSS", "time field format (YYYY-MM-DDTHH:mm:SS.ssssss)")
 	fs.IntVar(&config.DateColumn, "tc", 1, "ordinal number of the column with time")
 	fs.IntVar(&config.PivotColumn, "pc", 0, "pivot column")
@@ -83,6 +85,10 @@ func readCommandLineArguments(config *Configuration, args []string) (fs *flag.Fl
 	case 0 < fs.NArg():
 		config.InputFiles = fs.Args()
 	default:
+		config.InputFiles = []string{""}
+	}
+
+	if len(config.OutputFile) != 0 && 1 < len(config.InputFiles) {
 		config.printUsage = true
 	}
 
diff --git a/statecontext/config_test.go b/statecontext/config_test.go
index a1f1cae..bcf594e 100644
--- a/statecontext/config_test.go
+++ b/statecontext/config_test.go
@@ -23,13 +23,15 @@ func Test_readCommandLineArguments(t *testing.T) {
 				printUsage: false}, errEmptyArgumentList}},
 		{"test 1", []string{"programname"},
 			want{Configuration{
+				InputFiles:  []string{""},
 				DateFormat:  "YYYYMMDDHHmmSS",
 				DateColumn:  1,
 				Delimiter:   " ",
 				programName: "programname",
-				printUsage:  true}, nil}},
+				printUsage:  false}, nil}},
 		{"help", []string{"programname", "-h"},
 			want{Configuration{
+				InputFiles:  []string{""},
 				DateFormat:  "YYYYMMDDHHmmSS",
 				DateColumn:  1,
 				Delimiter:   " ",
@@ -37,18 +39,20 @@ func Test_readCommandLineArguments(t *testing.T) {
 				printUsage:  true}, nil}},
 		{"dateFormat", []string{"programname", "-t", "YYMMDDHHmm"},
 			want{Configuration{
+				InputFiles:  []string{""},
 				DateFormat:  "YYMMDDHHmm",
 				DateColumn:  1,
 				Delimiter:   " ",
 				programName: "programname",
-				printUsage:  true}, nil}},
+				printUsage:  false}, nil}},
 		{"dateColumn", []string{"programname", "-tc", "2"},
 			want{Configuration{
+				InputFiles:  []string{""},
 				DateFormat:  "YYYYMMDDHHmmSS",
 				DateColumn:  2,
 				Delimiter:   " ",
 				programName: "programname",
-				printUsage:  true}, nil}},
+				printUsage:  false}, nil}},
 		{"test 2", []string{"programname", "what"},
 			want{Configuration{
 				InputFiles:  []string{"what"},
diff --git a/toGraph.go b/toGraph.go
index d0a4192..276aefd 100644
--- a/toGraph.go
+++ b/toGraph.go
@@ -31,18 +31,41 @@ func main() {
 
 func run() {
 
-	for _, fileName := range state.Config().InputFiles {
-		inputFile, err := os.Open(fileName)
-		checkErr(err)
+	config := state.Config()
+	for _, fileName := range config.InputFiles {
+		inputFile := getInputStream(fileName)
+		outputFile, outName := getOutputStream(fileName, config)
 
-		outFilePath, outFileName := getOutFileName(fileName)
+		log.Printf("file being processed: %s", fileName)
+		processFile(inputFile, outputFile, config, outName)
+	}
+}
 
-		outputFile, err := os.OpenFile(outFilePath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0660)
-		checkErr(err)
+func getInputStream(fileName string) io.Reader {
+	if fileName == "" {
+		return os.Stdin
+	}
 
-		log.Printf("file being processed: %s", fileName)
-		processFile(inputFile, outputFile, state.Config(), outFileName)
+	inputFile, err := os.Open(fileName)
+	checkErr(err)
+
+	return inputFile
+}
+
+func getOutputStream(fileName string, config state.Configuration) (io.Writer, string) {
+	var outputName string
+	var outputPath string
+
+	if len(config.OutputFile) == 0 {
+		outputPath, outputName = getOutFileName(fileName)
+	} else {
+		_, outputName = getOutFileName(config.OutputFile)
+		outputPath = config.OutputFile
 	}
+	outputFile, err := os.OpenFile(outputPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0660)
+	checkErr(err)
+
+	return outputFile, outputName
 }
 
 func getOutFileName(fileName string) (outFilePath string, outFileName string) {