R for repaint does not always reload the file.
A workaround that always reloads the file is to press
hq, which will open the Help page, then quit. It has a side effect of forcing the file to reload.
 Here are some examples of situations that
R do and do not reload:
>> changes: DO get reloaded
sed -i, gEdit, TextEdit: DO NOT get reloaded
- On Linux,
vi changes: DO get reloaded
- On Mac,
vi changes: DO NOT get reloaded
I believe the difference comes down to whether the inode changes (you can check with
ls -i foo.txt). If the inode changes, then
R will not work.