If you directory have files like

-somefile_with_hyphen_as_first_char.txt

and you try to copy it and get an error like

cp -somefile_with_hyphen_as_first_char.txt something_else.txt

cp: invalid option — o

Because of the filename with hyphen act as a parameter, so you can’t just do regular cp.  Try this instead

cp — -somefile_with_hypgen_as_first_char.txt something_else.txt

Hope this will someone,l later