保护数据库连接字符串的最佳方法是什么?

I am writing a set of database-driven applications in PHP. These applications will run on a Linux server as its own user. Other users will likely be on the system at times, but have very controlled access. Other servers they will not have access to at all. I will also expose a limit stored procedure API to developers who need to write Perl scripts that access the database using a DBI and a set of functions I write.I am writing a set of database-driven applicati