Questions[merge](ubuntu)

There are lot of options for ffmpeg and other software, I tried "concat" method with ffmpeg and tried mkvmerge, they didn't work well for JPEG video (MJPG). I would use any tool that will keep quality, but preferably ffmpeg.

Here are specifications of the videos (they're both the same):

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '1.MOV':
  Metadata:
    major_brand     : qt  
    minor_version   : 537331972
    compatible_brands: qt  pana
  Duration: 00:00:30.00, start: 0.000000, bitrate: 29166 kb/s
    Stream #0:0(eng): Video: mjpeg (jpeg / 0x6765706A), yuvj420p(pc, bt470bg/unknown/unknown), 1280x720, 28486 kb/s, 30 fps, 30 tbr, 30 tbn, 30 tbc (default)
    Metadata:
      creation_time   : 2019-04-02T14:53:42.000000Z
      encoder         : Photo - JPEG
    Stream #0:1(eng): Audio: pcm_s16be (twos / 0x736F7774), 16000 Hz, mono, s16, 256 kb/s (default)

Whenever I try to install something, I get the same error:

Reading package lists... Error!
E: Encountered a section with no Package: header
E: Problem with MergeList /var/lib/apt/lists/repo.mongodb.org_apt_ubuntu_dists_bionic_mongodb-org_4.0_multiverse_binary-amd64_Packages
E: The package lists or status file could not be parsed or opened.

I've tried to do the following:

sudo rm -r /var/lib/apt/lists/*    
sudo apt-get clean && sudo apt-get update

which was the solution proposed in many places, but it didn't work.
Does anybody know how to fix this?

I am trying to a salvage an old scratched DVD by ripping it to ISO. I have two readers and created an ISO from each. Each reader is unable to read certain different bytes of the DVD and replaces them with 0s. When I compare the files using cmp -l file1.iso file2.iso, I see that certain bytes on the left are 0 while certain other bytes on the right are 0 (the corresponding bytes on the other files are non-zero). I want to create a 3rd file, say file3.iso that merges the non-zero differing bytes from the above two files. As an example, assume for simplicity that each file has 6 bytes as follows

file1.iso   file2.iso
---------   ---------
0           0
1           1
2           0
3           0
0           4
0           5

file3.iso should be as follows:

0
1
2
3
4
5

The files are quite large (around 8GB). Each file has the same number of bytes. I am using Ubuntu 16.04

Can anyone suggest the easiest way to do what I want. I can use the output of cmp -l as intermediate data but want to avoid writing code.

I know how to merge two tables to print alternative lines in a new file, but I want to merge every two lines from file1.txt with one line from file2.txt. As an example:

file1.txt is

A a aa
B b bb 
C c cc
D d dd

and file2.txt is

E e ee 
F f ff

I want to have

A a aa
B b bb 
E e ee 
C c cc
D d dd
F f ff

There are a lot of software in Windows to merge PDF files but how can we do the same in Ubuntu?