I create a tmp file "test.txt".
so , use "arc diff".
nano test.txt arc diff
Error msg:
You have a saved revision message in '.svn/arc/create-message'.
Message begins:
<<Replace this line with your Revision Title>>
You can use this message, or discard it.
Do you want to use this message? [Y/n] Y
Commit message has errors:
- Invalid or missing field "Title": Replace the line "<<Replace this
line with your Revision Title>>" with a human-readable revision title
which describes the changes you are making.
You must resolve these errors to continue.
Do you want to edit the message? [Y/n] n
Usage Exception: Message has unresolved errors. A copy was saved to '.svn/arc/create-message'.