Converting csv to xls

Hi,
Can anyone tell the option to change the file type in unix.
i.e. if a file is in csv(Comma Separating Values) format, it should be changed to xls(ordinary MS-Excel) format. But renaming command is not changing to correct file format.

Thanks in advance,
Milton.

Unix doesn't have any file types as in Windows.
*.csv,*.doc, etc.. are always considered as part of file name unlike windows. So even if you change the extension from CSV to XLS the format will not be changed.