How to open the default GUI text editor in Ubuntu or Lubuntu via a script?

I have a script that uses gedit to open text file in Ubuntu. That script does not work under Lubuntu. What command is required to execute the default text editor?

I want to make the script usable under Ubuntu and Lubuntu.

Use xdg-open it works in most linux distros.
example:

xdg-open /filepath/file.txt

You might get somewhere with /usr/bin/gnome-text-editor, as that's set using the alternatives system and points to the default editor under a gnome-ish environment. Not quite sure whether it is actually useful under lubuntu/kubuntu, but you could try.

Just to supplement Dennis' answer, with respect to Lubuntu 12.10, if one runs sudo update-alternatives --display gnome-text-editor, the output is:

gnome-text-editor - auto mode
  link currently points to /usr/bin/leafpad
/usr/bin/leafpad - priority 40
  slave gnome-text-editor.1.gz: /usr/share/man/man1/leafpad.1.gz
Current 'best' version is '/usr/bin/leafpad'.

And, as Dennis suggested, /usr/bin/gnome-text-editor does open Leafpad in Lubuntu.