File Management

[erict1689]

I am writing this program in which I open up a file and update that
information but to a new file.  I already have a global variable for
it but how do I go about creating an openable file in the source code?
 If it helps here is what I have:

def startUp():
    # Purpose: opens files and print report headings
    global empName, previousYTD, payRate, hoursWorked, recordCount,
eof, payFile, \
           payFileUpdated, newYTD, currentPay
    payFile=open("payroll.txt", "r")
    payFile.readline()
    

def readRecord():
    # Purpose: reads a record
    global empName, previousYTD, payRate, hoursWorked, recordCount,
eof, payFile, \
           payFileUpdated, newYTD, currentPay

    employeeRec = payFile.readline()
    if employeeRec == "":
        eof = True
    else:
        # parse file line for record fields and format/convert for
final output
        empName = employeeRec[0:25].strip()
        previousYTD = float(employeeRec[25:40])
        payRate = float(employeeRec[40:55])
        hoursWorked = float(employeeRec[55:70])
        recordCount += 1
        eof = False

def writeRecord():
    # Purpose: writes the updated record to the output file
    #Parameter
    global empName, previousYTD, payRate, hoursWorked, recordCount,
eof, payFile, \
           payFileUpdated, newYTD, currentPay
   
def processRecords():
    # Purpose: loops through input file and processes each record
    global empName, previousYTD, payRate, hoursWorked, recordCount,
eof, payFile, \
           payFileUpdated, newYTD, currentPay
    
    while not eof:
        calculatePay()
        printReportLine()
        writeRecord()
        readRecord()

def calculatePay():
    # Purpose: calculates pay and updated YTD
    # Return values: float - calculated pay, float - updated YTD amount 
    global empName, previousYTD, payRate, hoursWorked, recordCount,
eof, payFile, \
           payFileUpdated, newYTD, currentPay
    
def printReportLine():
    # Purpose: prints employee pay information
    # Parameters passed: float - calculated pay, float - updated YTD
amount
    global empName, previousYTD, payRate, hoursWorked, recordCount,
eof, payFile, \
           payFileUpdated, newYTD, currentPay

def closeUp():
    # Purpose: end of program housekeeping
    global empName, previousYTD, payRate, hoursWorked, recordCount,
eof, payFile, \
           payFileUpdated, newYTD, currentPay
   
    payFile.close()
    payFileUpdated.close()
    print "\nNumber of records in the file was",recordCount

Any and all help is appreciated.