If You want to rename the file "deadman.txt" into new name "aliveman.txt", then below line will rename the file.
If you want to move the file into another directory/folder, then code will be
rename("deadman.txt","c:\\deadman.txt"); # windows
rename("deadman.txt","/root/deadman.txt"); # linux
Although you can use the mv command from Linux by using system() function. Lots of choice and ways to do in Perl.