I'm deploying nutch. At first I just left the index file under `/root/nutch1.0`. This works fine when run from command line. However, when I search from web, it always returns `0 hit`.

I finally found the reason: It's because the index file is located under `/root` that causes the failure to open the file. Things returned to normal when I move the index file to another directory.

But my question is:

I didn't change the permissions of the index file (just `cp` xxx another-directory). Why did the access rights change?

```
drwxr-x--- 12 root root    4096 Jun  1 14:49 root
drwxr-xr-x 14 root root    4096 Nov 16  2007 usr

```

I put files under `/usr` and it worked.