C:\Projects_Perl\testing>echo "this is orginial file" > originalfile.txt

C:\Projects_Perl\testing>echo "this the new file" > newfile.txt

C:\Projects_Perl\testing>rename newfile.txt originalfile.txt
A duplicate file name exists, or the file
cannot be found.

C:\Projects_Perl\testing>rename originalfile.txt  originalfile.bak

C:\Projects_Perl\testing>rename newfile.txt originalfile.txt

C:\Projects_Perl\testing>type originalfile.txt
"this the new file"

C:\Projects_Perl\testing>