DOS command to copy multiple files?

Depends on which operating system you are using and whether you want to copy more than one file.

In DOS/Windows command prompt "c:\copy xxxx /destination_folder/"
if more than one file you can use "c:\copy xxx.* /destination_folder/"

Xcopy has more options (verify, copy subdirectories ..) and is used "c:\xcopy xxx* /s /destination_folder/"

In Unix/Linux/OSX cp is the command for copying
as in "#darkstar$cp -R *.txt /destination_folder/"
cp has a lot more option than xcopy but you will need to type either "cp --help" or "man cp" to get the best of cp's actions.