Python : Find Common Text in Two Files

Question

Let me give the example text files :

e.g. in file1.txt The data is:-

qwer
asdf
zxcv
1234

in file2.txt The data is:-

0987
5678
uiop
qwer
zxcv

Desired result:

qwer
zxcv

How do I get this result? I want to use python or gawk or sed.

Answer 1

I'd use Python sets for this:

file1 = set(line.strip() for line in open('file1.txt'))
file2 = set(line.strip() for line in open('file2.txt'))

for line in file1 & file2:
    if line:
        print line

Answer 2

Use comm:

comm -12 <(sort file1.txt) <(sort file2.txt)

With gawk:

gawk 'NR==FNR {file1[$0]++; next} $0 in file1' file1.txt file2.txt