Read text file content line-by-row with Linux shell __linux

It's a lot better than writing code:

ubuntu@vm-0-13-ubuntu:~$ cat a.txt
gaga   agagag
agaga   agagd   xxx
agadaa   Agaoo yyy zzzz
ubuntu@vm-0-13-ubuntu:~$ 
ubuntu@vm-0-13-ubuntu:~$ 
ubuntu@vm-0-13-ubuntu:~$ cat a.sh 
Cat A.txt | While read line
did
    echo $line >> b.txt
done

ubuntu@vm-0-13-ubuntu:~$ 
ubuntu@vm-0-13-ubuntu:~$ 
ubuntu@vm-0-13-ubuntu:~$ 
ubuntu@vm-0-13-ubuntu:~$ rm b.txt
ubuntu@vm-0-13-ubuntu:~$ 
ubuntu@vm-0-13-ubuntu:~$ 
ubuntu@vm-0-13-ubuntu:~$ 
ubuntu@vm-0-13-ubuntu:~$./a.sh 
ubuntu@vm-0-13-ubuntu:~$ 
ubuntu@vm-0-13-ubuntu:~$ 
ubuntu@vm-0-13-ubuntu:~$ 
ubuntu@vm-0-13-ubuntu:~$ cat b.txt 
gaga agagag
agaga agagd xxx
Agadaa Agaoo yyy zzzz

Get.