Python正则表达式：用户输入多个搜索词

Question

What my code is suppose to do is take in user input search terms then iterate through a tcp dump file and find every instance of that term by packet. The src IP acts as the header to each packet in my output.

So I am having an issue with the fileIn being seemingly erased when it iterates through the first term. So when the program goes to look at the second user input search term it obviously can't find anything. Here is what I have:

import re
searchTerms = []

fileIn = open('ascii_dump.txt', 'r')

while True:
    userTerm = input("Enter the search terms (End to stop): ")
    if userTerm == 'End':
        break
    else:
        searchTerms.append(userTerm)

ipPattern = re.compile(r'((?:\d{1,3}\.){3}\d{1,3})')

x = 0

while True:
    print("Search Term is:", searchTerms[x])
    for line in fileIn:
        ipMatch = ipPattern.search(line)
        userPattern = re.compile(searchTerms[x])
        userMatch = userPattern.search(line)

        if ipMatch is not None:
            print(ipMatch.group())

        if userMatch is not None:
            print(userMatch.group())
    x += 1
    if x >= len(searchTerms):
       break

Answer 1

This happens because you opened the file object as an iterator which is consumed in the first past through the for loop.

During the second time through the loop, the for line in fileIn will not be evaluated since the iterator fileIn has already been consumed.

A quick fix is to do this:

lines = open('ascii_dump.txt', 'r').readlines()

then in your for loop, change the for line in fileIn to:

for line in lines:

Having said this, you should rewrite your code to do all regex matches in a single pass using the regex or operator.

Answer 2

You need to "rewind" the file after the for line in fileIn loop:

...
fileIn.seek(0);
x += 1