You might find the glob function more useful in this situation:
import glob
for file in glob.glob("/Users/shirin/Desktop/Artez/untitled.*"):
print(file)
Your function does not print anything as there are probably no files ending with .* in the name. The glob.glob() function will carry out the file expansion for you.
You can then use this to do your file renaming as follows:
import glob
import os
from datetime import datetime
current_day = datetime.now().strftime("%Y-%m-%d")
for source_name in glob.glob("/Users/shirin/Desktop/Artez/untitled.*"):
path, fullname = os.path.split(source_name)
basename, ext = os.path.splitext(fullname)
target_name = os.path.join(path, '{}{}'.format(current_day, ext))
os.rename(source_name, target_name)
A Python datetime object can be used to get you a suitable timestamp.
if file.startswith("untitled")?