How to compare two lists and print the difference in one list

Question

I'm trying to extract usernames from a config file into a list and compare the usernames against another secure list of usernames. The config file looks like this this:

username Hilton privilege 15 password 0 $xxxxxxxxxxxxx
username gooduser password 0 $xxxxxxxxxxxxx
username jason secret 5 $xxxxxxxxxxxxx

The problem with the output is not a single list! (each user is in a list)

['Hilton']
['gooduser']
['jason']

I am reading the file into one single list. Then located the 'username' position and used enumerate to find the position

the_list = []

with open('config_file.txt', "r") as f:
    the_list = f.read().split()        
    print(the_list)
    find_keyword = 'username'

    secure_users = ['jason','test','admin']

for i,x in enumerate(the_list):   # search in the list
  if x=='username':               # for this keyword 'username'
     pos = i + 1                  # position of every username 

     print(the_list[pos].split())          # print all users.

#Compare secure_users[] vs the_list[] here

the expected output is a list like >> ['Hilton','gooduser','jason']

So that I can compare it against the secure_users list

Answer 1

Try the following:

usernames = []
secure_users = ['jason','test','admin']
with open('config_file.txt', "r") as f:
    for line in f:
        usernames.append(line.split()[1])

print([user for user in secure_users if user in usernames])

Answer 2

Made some modification to your code,

the_list = []

with open('config_file.txt', "r") as f:
    the_list = f.read().split()        
    print(the_list)
find_keyword = 'username'

secure_users = ['jason','test','admin']

users_list = []
for i,x in enumerate(the_list):   # search in the list
    if x=='username':               # for this keyword 'username'
        pos = i + 1                  # position of every username 

        users_list.append(the_list[pos].split()[0])          # print all users
print(users_list)

---

Output:

['username', 'Hilton', 'privilege', '15', 'password', '0', '$xxxxxxxxxxxxx', 'username', 'gooduser', 'password', '0', '$xxxxxxxxxxxxx', 'username', 'jason', 'secret', '5', '$xxxxxxxxxxxxx']
['Hilton', 'gooduser', 'jason']

Another solution:(Best way)

with open('config_file.txt', 'r') as f:
    data = f.read().split()
    user_names = [data[i+1] for i,line in enumerate(data) if 'username' in line ]

---

Output:

['Hilton', 'gooduser', 'jason']

Answer 3

Using Regex.

Ex:

import re

find_keyword = 'username'
the_list = []
with open('config_file.txt') as f:
    for line in f:
        m = re.search(r"\b{}\b \b(.*?)\b ".format(find_keyword), line.strip())    #Search for key and word after that. 
        if m:
            the_list.append(m.group(1))

print(the_list)# ->['Hilton', 'gooduser', 'jason']

Answer 4

add a list named diff in your code like :

diff = []

then Just add below 2 lines after your code line print(the_list[pos].split()):

if the_list[pos] not in secure_users:
        diff.append(the_list[pos])

then print diff to see the single list:

print(diff)