converting an Excel (xls) file to a comma separated (csv) file without the GUI

Solution 1:

You can use xls2csv from the catdoc package if you're on Debian/Ubuntu

Solution 2:

In Java world you can use apache poi. You could start from the following Groovy snippet.

FileInputStream fis = new FileInputStream(filename);
Workbook wb = new HSSFWorkbook(fis); 
Sheet sheet = wb.getSheetAt(0);
for (Row row : sheet) {
  for (Cell cell : row) {
    doSomething(cell.toString())
  }

}