Understanding the `diff` Command in Unix-like Operating Systems

`diff` is a command-line utility in Unix-like operating systems that compares two files and shows the differences between them. It takes two file names as arguments, and displays the lines that are present in one file but not the other.

For example, if you run `diff file1 file2`, it will show you the lines that are present in `file1` but not in `file2`. If there are any differences, the output will look something like this:
```
1c1
> hello
---
> world
```
This means that the line "hello" is present in `file1` but not in `file2`, and the line "world" is present in `file2` but not in `file1`.

You can also use `diff` to compare multiple files at once. For example, if you run `diff file1 file2 file3`, it will show you the differences between all three files.

I hope that helps! Let me know if you have any other questions.