adds --output flag

cmd/renderizer/main.go

@@ -8,9 +8,9 @@ import (
 	"path/filepath"
 	"strings"
 
+	"github.com/gomatic/renderizer/v2/pkg/renderizer"
 	"github.com/imdario/mergo"
 	"github.com/kardianos/osext"
-	"github.com/gomatic/renderizer/v2/pkg/renderizer"
 	"github.com/urfave/cli/v2"
 	"gopkg.in/yaml.v2"
 )
@@ -123,6 +123,13 @@ func main() {
 			EnvVars:     []string{"RENDERIZER_VEBOSE"},
 			Destination: &settings.Options.Verbose,
 		},
+		&cli.StringFlag{
+			Name:        "output",
+			Aliases:     []string{"o"},
+			Usage:       "writes template to output file rather than stdout",
+			Value:       settings.Options.Output,
+			Destination: &settings.Options.Output,
+		},
 	}
 
 	app.Before = func(ctx *cli.Context) error {
@@ -241,7 +248,7 @@ func main() {
 					flag = parts[0]
 				}
 				switch flag[2:] {
-				case "settings", "missing", "environment", "env":
+				case "settings", "missing", "environment", "env", "output":
 					// If the flag requires a parameter but it is not specified with an =, grab the next argument too.
 					if !strings.Contains(larg, "=") {
 						next = true

pkg/renderizer/renderizer.go

@@ -44,6 +44,8 @@ type Options struct {
 	Verbose bool
 	//
 	Testing bool
+	//
+	Output string
 }
 
 //
@@ -215,7 +217,19 @@ func (settings *Options) Render() error {
 			}
 
 			data = b.Bytes()
-			fmt.Println(string(data))
+			fh := os.Stdout
+
+			if settings.Output != "" {
+				if fh, err = os.Create(settings.Output); err != nil {
+					log.Print(err)
+					return 8
+				}
+			}
+
+			if _, err = fh.Write(data); err != nil {
+				log.Print(err)
+				return 8
+			}
 
 			return 0
 		}()