How can I know the lucene index version from files

I have this lucene index files, in a directory:

```
$ ls
_1p.fdt  _1p.fdx  _1p.fnm  _1p_Lucene41_0.doc  _1p_Lucene41_0.pos  _1p_Lucene41_0.tim  _1p_Lucene41_0.tip  _1p.nvd  _1p.nvm  _1p.si  segments_1  segments.gen  write.lock
```

 - How can I know which is the version of this lucene index?
 - Which codec does it uses?
 - What command line do I use (in a terminal) to create a lucene index
  with the same version as the files above?

Cheers.