Need help optimizing first script

[Frederic Lafleche]

I put this script together mainly from bits and pieces I picked up in
this newsgroup and one or two books lying around. What it does is map
a given NT network drive and copy a file to it if some conditions are
met.  As this is my first script, I'm looking for ways to improve code
in any possible way, whether it's overall design, style, grammar,
logic, readability, performance, validation, anything.

#copyacs.py
import os, shutil, sys, time, win32file
from win32wnet import WNetAddConnection2, error

# Functions

# Generate timestamp
# OUTPUT: string in yyymmddhhmm format
def determineFN():
    # Get current time
    now = time.time()
    # Parse elements
    (Iyear, Imonth, Iday, Ihour, Iminute) = (time.localtime(now)[:5])
    year = str(Iyear)
    month = str(Imonth)
    day = str(Iday)
    hour = str(Ihour)
    minute = str(Iminute)
      
    # Padding
    if len(month) == 1:
        month = '0' + month
    if len(day) == 1:
        day = '0' + day
    if len(hour) == 1:
        hour = '0' + hour
    if len(minute) == 1:
        minute = '0' + minute

    return year + month + day + hour + minute

# Map network drive
def use (drive, host, user, passwd):
    try:
        WNetAddConnection2 (1, drive, host, None, user, passwd)
        return 0
    except error:
        return 1

# Variable assignments

devicename = 'I:' # Enter network drive number.  Ex. format: 'Z:'
dirTarget = devicename + '\\it\\popup' # Enter target path.
sharename = '\\\\afs\\grps'            # Enter shared resource name.  
username = 'login' # Enter user account inside single quotes
password = 'password' # Enter user password inside single quotes
drives = []                                 
drivemask = win32file.GetLogicalDrives()    # Bitmask
acsMode = sys.argv[1]    # Get second command-line argument of list.
                         # (First argument is program name.)
dirSource = 'd:\\oracle\\acs\\' + acsMode   # Source directory
acsfile = 'import.txt'                      # File to copy
sourceacsfile = dirSource + '\\' + acsfile  # Absolute path

# Main body

fDate = determineFN()
execlog = dirSource + '\\logs\\trace' + fDate + '.log'                
         # Operations log
timestring = time.strftime("%Y-%m-%d %H:%M:%S",
time.localtime(time.time()))    # Timestamp

if os.path.isdir(dirSource + '\\logs'):     # Log path exists?
    fObject = open (execlog, 'w')
    fObject.write(timestring + '\n')
else:
    sys.exit()

# List drives
for drive in range(ord("A"), ord("Z") ):
     if drivemask & 1 != 0:
          drives.append( chr(drive) )
     drivemask = drivemask >> 1

# Cut ":" suffix off devicename.
# To test whether a value is in the list, use *in*,
# which returns 1 if the value is found or 0 if it is not.

# If drive not mapped, map it.
if devicename[0] not in drives:
    if not (use(devicename, sharename, username, password)):
        fObject.write('Cannot map device.\n')
  
if os.path.isfile(sourceacsfile):           # Source file exists?
    if os.path.isdir(dirTarget):            # Target path exists?
        shutil.copyfile(sourceacsfile, dirTarget + '\\' + acsfile)
        fObject.write(sourceacsfile + ' copied.\n')
        if os.path.isdir(dirSource + '\\sav'):
            os.rename(sourceacsfile, dirSource + '\\sav\\import' +
fDate + '.txt')
    else:
        fObject.write('Cannot access destination path ' + dirTarget +
'.\n')
else:
    fObject.write('Source file ' + sourceacsfile + ' does not
exist.\n')
    fObject.write('Transfer aborted.\n')

fObject.close()

# End of main body