The first way to search for a file in all a filesystem is to use the command locate
With Debian, locate is no more included in the package findutils.
You must install the package locate which provides the commands locate and updatedb.
As root :
root@localhost:~#apt-get install locate
Then, issue the following command to check whether the commands locate and updatedb are available :
The command locate looks through an index for searching a file.
This index is built after issuing the command updatedb as root :
The more recent the index is, the more efficient is the search through locate.
Make sure that the index is rebuilt on a regular basis. This point is all the more crucial since there are a lot of files creation/deletion. The index could be outdated very quickly.