I am familiar with tools such as tkDiff and WinMerge and am aware of how to see the difference between two files.

What I'm looking to do is to produce a report of elements in one file that are not present in another.

For example:

File1 contains:

```
apple
cool
dude
flan

```

File2 contains:

```
apple
ball
cool
dude
elephant

```

I want to produce a report that contains:

```
ball
elephant

```

Or, better yet, a report like this:

```
+ball
+elephant
-flan

```

Does anybody know of a tool that can do this? Preferably with command line options.

The report feature in WinMerge isn't too far off what I'd like but there is no command line option to do this (as far as I know).

Thanks in advance.