Error in simple python module

Question

I tried to write a little python script today but have failed horribly. Why is it that the code below gives me the following error after being called from the shell?

Error

File "./testmod.py", line 15, in <module>
    printdnsfile(sys.argv[1])
  File "./testmod.py", line 10, in printdnsfile
    print(socket.gethostbyname(str(line)))
socket.gaierror: [Errno 8] nodename nor servname provided, or not known

Code

#!/usr/bin/python

def printdnsfile(file):
    file= open (file,"r")
    import socket
    dest = open("/dnsfile.txt",'w')
    for line in file:
        print(socket.gethostbyname(str(line)))
        print>>dest, str(",".join([line,socket.gethostbyname(line)])+'\n')

if __name__ == "__main__":
    import sys
    printdnsfile(sys.argv[1])

I tested the socket module in the python-console and it worked as expected. Is there an error with my code or is this a problem with my configuration?

Thanks.

secretmike · Accepted Answer · 2012-02-07 22:42:55Z

2

You might have an empty line in your input file. Try checking your line before you gethostbyname.

def printdnsfile(file):
    file= open (file,"r")
    import socket
    dest = open("/dnsfile.txt",'w')
    for line in file:
        line = line.strip()
        if line:
            print(socket.gethostbyname(str(line)))
            print>>dest, str(",".join([line,socket.gethostbyname(line)])+'\n')

answered Feb 7, 2012 at 22:42

secretmike

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2 Comments

Julian Over a year ago

I don't have an empty line in my input file, however my problem nevertheless got fixed by using your suggestion :). Curious why that is though. Anyway, Thank you!

secretmike Over a year ago

Don't forget about the final line in the file. Sometimes it doesn't show up very well in your text editor. That could be it.

jcollado · Accepted Answer · 2012-02-07 22:41:53Z

1

Probably the problem is that line doesn't contain the expected value. To make sure about that you could add a print line statement before the line that is failing or use pdb to debug the program.

answered Feb 7, 2012 at 22:41

jcollado

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