copyurl: add --stdout flag to write to stdout

cmd/copyurl/copyurl.go

@@ -2,6 +2,8 @@ package copyurl
 
 import (
 	"context"
+	"errors"
+	"os"
 
 	"github.com/rclone/rclone/cmd"
 	"github.com/rclone/rclone/fs"
@@ -12,37 +14,55 @@ import (
 
 var (
 	autoFilename = false
+	stdout       = false
 )
 
 func init() {
 	cmd.Root.AddCommand(commandDefinition)
 	cmdFlags := commandDefinition.Flags()
-	flags.BoolVarP(cmdFlags, &autoFilename, "auto-filename", "a", autoFilename, "Get the file name from the url and use it for destination file path")
+	flags.BoolVarP(cmdFlags, &autoFilename, "auto-filename", "a", autoFilename, "Get the file name from the URL and use it for destination file path")
+	flags.BoolVarP(cmdFlags, &stdout, "stdout", "", stdout, "Write the output to stdout rather than a file")
 }
 
 var commandDefinition = &cobra.Command{
 	Use:   "copyurl https://example.com dest:path",
 	Short: `Copy url content to dest.`,
 	Long: `
-Download urls content and copy it to destination 
-without saving it in tmp storage.
+Download a URL's content and copy it to the destination without saving
+it in temporary storage.
 
-Setting --auto-filename flag will cause retrieving file name from url and using it in destination path. 
+Setting --auto-filename will cause the file name to be retreived from
+the from URL (after any redirections) and used in the destination
+path.
+
+Setting --stdout or making the output file name "-" will cause the
+output to be written to standard output.
 `,
-	Run: func(command *cobra.Command, args []string) {
-		cmd.CheckArgs(2, 2, command, args)
+	RunE: func(command *cobra.Command, args []string) (err error) {
+		cmd.CheckArgs(1, 2, command, args)
 
 		var dstFileName string
 		var fsdst fs.Fs
-		if autoFilename {
-			fsdst = cmd.NewFsDir(args[1:])
-		} else {
-			fsdst, dstFileName = cmd.NewFsDstFile(args[1:])
+		if !stdout {
+			if len(args) < 2 {
+				return errors.New("need 2 arguments if not using --stdout")
+			}
+			if args[1] == "-" {
+				stdout = true
+			} else if autoFilename {
+				fsdst = cmd.NewFsDir(args[1:])
+			} else {
+				fsdst, dstFileName = cmd.NewFsDstFile(args[1:])
+			}
 		}
-
 		cmd.Run(true, true, command, func() error {
-			_, err := operations.CopyURL(context.Background(), fsdst, dstFileName, args[0], autoFilename)
+			if stdout {
+				err = operations.CopyURLToWriter(context.Background(), args[0], os.Stdout)
+			} else {
+				_, err = operations.CopyURL(context.Background(), fsdst, dstFileName, args[0], autoFilename)
+			}
 			return err
 		})
+		return nil
 	},
 }