This is one that puzzles many novice UNIX/Linux users. From time to time, one comes across a file with a weird filename such as -abc.jpg and runs into problems when trying to delete it or rename it because the shell interprets the dash (-) as a special symbol after which it should expect a flag/option. Well, here is the solution to remove or rename those files (actually, either of these will work):

rm -- -abc.jpg
rm ./-abc.jpg