Very basic security question:

["Ing. Bernardo Lopez" <bloodk () prodigy net mx>]

How secure could be my webserver if i allow some php scripts to modify
the file (directly) /etc/passwd & /etc/shadow but my script will only
allow to modify the line of the loged user (like userid=visitor, then he
only can see/modify visitor's line)??

It is secure, if i enforce very enougth the security of the script... or
this stills being a stupid option?

Also if i use that script only for modify the permisions of ftp's users
it stills unsecure? (if the ftpd runs whit a very unpriviligiated uid?)

Thanks in advance