You need to have win32com installed on your machine. Here is my code:

import win32com.client as win32
fname = "full+path+to+xls_file"
excel = win32.gencache.EnsureDispatch('Excel.Application')
wb = excel.Workbooks.Open(fname)

wb.SaveAs(fname+"x", FileFormat = 51)    #FileFormat = 51 is for .xlsx extension
wb.Close()                               #FileFormat = 56 is for .xls extension
excel.Application.Quit()

Just wrapped the code above in a function together with better path handling to make sure the excel process is getting closed.

from pathlib import Path
import win32com.client as win32
    
def convert_xls_to_xlsx(path: Path) -> None:
    excel = win32.gencache.EnsureDispatch('Excel.Application')
    wb = excel.Workbooks.Open(path.absolute())

    # FileFormat=51 is for .xlsx extension
    wb.SaveAs(str(path.absolute().with_suffix(".xlsx")), FileFormat=51)
    wb.Close()
    excel.Application.Quit()

If you're comfortable with Python first install the xlrd module, which is useful for reading Excel files. You can get by doing:

% easy_install xlrd

in the Terminal.

Then give this rough script a try.

#! /usr/bin/env python

import xlrd
import csv

book = xlrd.open_workbook('an_excel_file.xls')

# Assuming the fist sheet is of interest 
sheet = book.sheet_by_index(0)

# Many options here to control how quotes are handled, etc.
csvWriter = csv.writer(open('a_csv_file.csv', 'w'), delimiter='|') 

for i in range(sheet.nrows):
    csvWriter.writerow(sheet.row_values(i))

Run this script from the directory where the Excel file is located (an_excel_file.xls in the script) by invoking python xls_to_csv.py at the Terminal

There are a number of options for the xlrd objects, as well as the csv module, so check out the following if you need to tweak the settings:

• http://www.python-excel.org/
• Python Excel Tutorial
• CSV Module