"Minus" operation on two files using Linux commands

Question

I have 4 files sorted alphabetically, A, B, C, and D. These files contain a single string on each line. Essentially, what needs to happen is that anything in B gets deleted from A. The result of that will then be stripped of anything in C. And similarly, the result of that will be stripped of D. Is there a way to this using Linux commands?

Accepted Answer

`comm` is good for this, either:

```
cat B C D | sort | comm -2 -3 A -
```

or:

```
comm -2 -3 A B | comm -2 -3 - C | comm -2 -3 - D
```

depending on what's easier/clearer for your script.

"Minus" operation on two files using Linux commands

Solution

Problem