In Ubuntu GUI, to change the name of a file we can press F2. Then the name of the file will highlight, excluding the file extension. What is the keyboard shortcut to place the cursor at the end of the filename, that is after the last character of the filename (and before the extension)?
Press F2 to edit the filename.
Press End to move the cursor at the end of the name.
Press Home to move the cursor at the beginning of the name.
Just like you do in a text editor. Does work for me in Xubuntu 16.04 and Thunar and PCManFM. It's kinda universal. It works in Windows too.
After clicking the filename and pressing F2
press the right arrow key ->
and then press the left arrow key <- a couple of times until you get to the front of the extension.
Not a shortcut, but still quite short ;)