python iterating through and writing to a file

Question

I need to write a function that opens two files and if a certain comparison is true write the result to a third file:

def crack_pass_file(pass_filename,words_filename,out_filename):
    f1=open(pass_filename)
    f2=open(words_filename)
    f3=open(out_filename,'w')
    for line1 in f1:
        x=make_dictionary(line1.split(":"))
        password=x["password"]
        name=x["account"]
        for line2 in f2:
            if (check_pass(line2.strip(),password)==True):
                f3.write(name + "="+line2.strip())

File f1 is a file containing:

root:VgzdTLne0kfs6:0:0:Corema Latterll:/home/root:/bin/bash
checani:IqAFDoIjL2cDs:1:1:Pengpu Checani:/home/checani:/bin/bash
rkrakow:DLD3nJmCvt3pY:2:2:Rodentia Krakow:/home/rkrakow:/bin/bash
forkland:oWMVyy1FTdNL6:3:3:Forkland Maskins:/home/forkland:/bin/bash
obongo:O44lPEloqk5tY:4:4:Obongo Obwalden:/home/obongo:/bin/bash
pglenda:xboW5dHcsqvSQ:5:5:Pahsien Glenda:/home/pglenda:/bin/bash
madel:qEHvJXMkTSAZA:6:6:Madel Aporosa:/home/madel:/bin/bash
ssauks:Q3Kz1z7eAiwjg:7:7:Schober Sauks:/home/ssauks:/bin/bash
slajoie:wWTHgoE8SC8W6:8:8:Scheiner Lajoie:/home/slajoie:/bin/bash
tieton:RWORYLxRSSzMU:9:9:Lerwa Tieton:/home/tieton:/bin/bash

where each line has a user, a password, and a bunch of other things. For line 1 root is the user and VgzdTLne0kfs6 is the encrypted password. Same format is used for every other line. What I need to do is take the encrypted password and see if calling crypt on a password in the other file, f2, which contains a giant list of words in alphabetical order like:

embordering
emborders
emboscata
embosk
embosked
embosking

will make that password into the encrypted password. I already have the function that does that and it works:

def check_pass(plain,enc):
    s = enc[0:2]
    x = crypt.crypt(plain, s)
    if x==enc: return True
    else: return False

also here is the makedictionary function that I use to make a dictionary out of every line of file 1, also works Ive tested it:

def make_dictionary(s):
    d={}
    d["account"]=s[0]
    d["shell"]=s[6]
    d["UID"]=int(s[2])
    d["GID"]=int(s[3])
    d["GECOS"]=s[4]
    d["directory"]=s[5]
    d["password"]=s[1]
    return d

when I test this it writes: root=stroam to the output file, which is the decrypted password for the first user but doesnt write any of the rest. This should be the result:

root=stroam
checani=asarta
rkrakow=sinklike
obongo=yawnful
madel=aviatic
tieton=dagesh
pglenda=sngissa
forkland=relliarb
slajoie=mu2j1k
ssauks=EGaFeIHC

I found all these words(yawnful, aviatic, etc ) in the words file but for some reason they are not being matched. Ive also tried doing like: check_pass("asarta","IqAFDoIjL2cDs") and some others and they all return true so Im confused why more of them arent printed out to my output file.

Answer 1

You want to evaluate every line in f1 against every line in f2 . But you consume every line in f2 on the first iteration through f1 . On the second iteration, f2 is empty and you won't enter the body of this loop.

for line1 in f1:
# ...
    for line2 in f2:

Instead, outside of your for line in f1 loop, generate a list of the lines in f2 (and optionally f1) like so:

f2_lines = [line2 for line2 in f2]
...
for line1 in f1:

Now you can use

for line2 in f2_lines:

in the body of your f1 loop.

Answer 2

The first time you iterate f2 , you exhaust the iterator, and all future iterations of f2 are loops that don't execute at all. Either load all the lines of f2 into a list so it can be iterated multiple times, or call f2.seek(0) after exhausting it to reset the file pointer.