next : um next calls (um--header) and only prints the filename for piping : no more auto open

um.el

@@ -358,27 +358,16 @@ Prefix arg prompts for the directory instead.
 + tags
 
 "
-  (insert
-   (format "# %s\n: %s%s" filename (format-time-string um--date-format) um--header-end))
-  (when tags
-    (forward-line -1)
-    (dolist (tag (split-string tags ","))
-      (insert (format "+ %s\n"
-                      (if (equal "+" tag)
-                          (cadr (split-string filename "\\."))
-                        tag))))
-    (forward-line)))
-
-;;;###autoload
-(defun um-next (filename &optional tags)
-  "Takes the filename generated by the CLI, opens it, and adds the header.
-
-Optional TAGS string may contain more than one tag separated by a comma.
-
-A tag with a value of \"+\" is rendered as the descriptor portion of the filename.
-"
-  (find-file filename)
-  (um--header filename tags))
+  (with-temp-buffer (insert
+                     (format "# %s\n: %s%s" filename (format-time-string um--date-format) um--header-end))
+                    (when tags
+                      (forward-line -1)
+                      (dolist (tag (split-string tags ","))
+                        (insert (format "+ %s\n"
+                                        (if (equal "+" tag)
+                                            (cadr (split-string filename "\\."))
+                                          tag)))))
+                    (buffer-string)))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;; um-minor-mode