mv [-i] filename1 filename2means change the name of filename1 to filename2. If filename2 already exists, it overwrites the file, unless the -i option is used, in which case a confirmation by the user will be necessary.
mv [-i] filename... directorywill move filename..., i.e., a number of files, into directory directory. If a named file name already exists within directory, it will be overwritten unless the -i option was used, in which case a confirmation by the user will be needed.
Write permission on directory is essential.