How to use diff with multiple files?

That's a very good question, and an important one for real-world scenarios!

The diff command is primarily designed to compare two files at a time.

So, when you ask "How to use diff with multiple files?", diff doesn't inherently compare, say, file1 vs file2 vs file3 all in one go to show you a consolidated difference report. Instead, you would typically compare them pairwise:

Compare file1 and file2:
```
diff file1 file2
```
Compare file1 and file3:
```
diff file1 file3
```
Compare file2 and file3:
```
diff file2 file3
```

...and so on, depending on which files you want to check for differences against each other.

If you have a directory with many files and want to see differences between corresponding files in different directories, then you would use diff with the -r (recursive) option. For example, to compare dir1 and dir2:

diff -r dir1 dir2

This would go through both dir1 and dir2 and compare all files that have the same name in both directories, as well as report files that exist in one but not the other.

For the current step, we're sticking to comparing just two specific files, file1 and file2. But it's great that you're thinking about how these tools scale up!