Question: I have a classpath, something like:

```
myproject/classes;myproject/lib/somecrab.zip;myproject/lib/somelib1.jar;myproject/lib/somelib2.jar;myproject/lib/somelib3.jar;

```

Now I would like to clean up this classpath and throw away somethings which I don't want anymore. Hence in this case the classpath should look something like

```
myproject/classes;myproject/lib/somelib1.jar;myproject/lib/somelib3.jar;

```

How can I do that with a regular expression? I want to do it with an ant-Script, e.g.

```
<pathconvert property="new.classpath" pathsep=";">
    <path refid="old.classpath" />
    <chainedmapper>
        <regexpmapper from="(.*).jar" to="\1.jar" />
    </chainedmapper>
</pathconvert>

```

How do I need to adapt the regexp? Thanks a lot!

Answer: 
If all you want to do is get rid of a contiguous string in the middle, it should just be:

```
<regexpmapper from="(.*)myproject/lib/somecrab.zip;(.*)" to="\1\2" />

```
I think you would need to phrase it as (validstuffbefore)skipstuff(validstuffafter) and then use a replace string of \1\2

So (possibly):

```
^([\w/]+;)((?:[\w/]+\.jar;)*)[\w/]+\.zip;?((?:[\w/]+\.jar;)*)$

```

And replace with:

```
\1\2\3

```

You may have issues with multiple matches, but the global flag *should* resolve that.

Good luck!