perldoc > rename(2)

    rename OLDNAME,NEWNAME
            Changes the name of a file; an existing file NEWNAME will be
            clobbered. Returns true for success; on failure returns false
            and sets $!.

            Behavior of this function varies wildly depending on your system
            implementation. For example, it will usually not work across
            file system boundaries, even though the system *mv* command
            sometimes compensates for this. Other restrictions include
            whether it works on directories, open files, or pre-existing
            files. Check perlport and either the rename(2) manpage or
            equivalent system documentation for details.

            For a platform independent "move" function look at the
            File::Copy module.

            Portability issues: "rename" in perlport.