bash: how run script when file is put into folger and how parse xml file via bash

[Dario Lesca]

hi, I'm looking for a method for do this thing:

a) when a file is put into a specific folder (via ftp or http or smb), a
shell script must be automatic run.

b) the file is a simple xml and I must parser it and convert it to a csv
file with bash script.

For a) i can use a cron job, but i'm looking for another solution more
efficient and started only when the file is come ...

For b) now I use grep+sed+awk, but I'm looking for a best and more solid
method for extract only some specific field from the file.

Someone can show me, if exist, more better solution for a) and b)?

Many thanks ... and sorry for my bad English :-)
  
-- 
Dario Lesca <d.lesca at solinos.it>