<P> A very primitive assembler and disassambler . </P> <P> The command has the ability to analyze the file fragmentation on a disk drive or to defragment a drive . This command is called DEFRAG in MS - DOS / PC DOS and diskopt in DR - DOS . </P> <P> DEL (or the alternative form ERASE) is used to delete one or more files . </P> <P> Deletes a directory along with all of the files and subdirectories that it contains . Normally, it will ask for confirmation of the potentially dangerous action . We know that the RD (RMDIR) command cannot delete a directory if the directory is not empty . DELTREE command can be used to delete the whole directory if the directory is not empty . </P>

Give five internal commands of dos with their syntaxes and examples