python - Script skips second for loop when reading a file

Question

I am trying to read a log file and compare certain values against preset thresholds. My code manages to log the raw data from with the first for loop in my function.

I have added print statements to try and figure out what was going on and I've managed to deduce that my second for loop never "happens".

This is my code:

def smartTest(log, passed_file):    
    # Threshold values based on averages, subject to change if need be
    RRER = 5
    SER = 5
    OU = 5
    UDMA = 5
    MZER = 5
    datafile = passed_file
    # Log the raw data    
    log.write('=== LOGGING RAW DATA FROM SMART TEST===\r\n')
    for line in datafile:
        log.write(line)
        log.write('=== END OF RAW DATA===\r\n')

        print 'Checking SMART parameters...',
        log.write('=== VERIFYING SMART PARAMETERS ===\r\n')

        for line in datafile:
            if 'Raw_Read_Error_Rate' in line:
                line = line.split()
                if int(line[9]) < RRER and datafile == 'diskOne.txt':
                    log.write("Raw_Read_Error_Rate SMART parameter is: %s. Value under threshold. DISK ONE OK!\r\n" %int(line[9]))
                elif int(line[9]) < RRER and datafile == 'diskTwo.txt':
                    log.write("Raw_Read_Error_Rate SMART parameter is: %s. Value under threshold. DISK TWO OK!\r\n" %int(line[9]))
                else:
                    print 'FAILED'
                    log.write("WARNING: Raw_Read_Error_Rate SMART parameter is: %s. Value over threshold!\r\n" %int(line[9]))
                    rcode = mbox(u'Attention!', u'One or more hardrives may need replacement.', 0x30)

This is how I am calling this function:

dataOne = diskOne()
smartTest(log, dataOne)
print 'Disk One Done'

diskOne() looks like this:

def diskOne():
    if os.path.exists(r"C:\Dejero\HDD Guardian 0.6.1\Smartctl"):
        os.chdir(r"C:\Dejero\HDD Guardian 0.6.1\Smartctl")
        os.system("Smartctl -a /dev/csmi0,0 > C:\Dejero\Installation-Scripts\diskOne.txt")
        # Store file in variable
        os.chdir(r"C:\Dejero\Installation-Scripts")
        datafile = open('diskOne.txt', 'rb')
        return datafile
    else:
        log.write('Smart utility not found.\r\n')

I have tried googling similar issues to mine and have found none. I tried moving my first for loop into diskOne() but the same issue occurs. There is no syntax error and I am just not able to see the issue at this point.

Bhargav Rao Bhargav Rao · Accepted Answer · 2015-03-06T15:24:23

It is not skipping your second loop. You need to seek the position back. This is because after reading the file, the file offset will be placed at the end of the file, so you will need to put it back at the start. This can be done easily by adding a line

datafile.seek(0);

Before the second loop.

Ref: Documentation

python - Script skips second for loop when reading a file

1 Answers