使用远程shell访问进行PHP调试

Question

I'm playing with a PHP weblog application using a shared hosting service, as a part of my PHP learning process. The service provider has a typical LAMP environment with remote ssh access.

Vim has been my best friend in exploring the PHP code. However, I found it sometimes hard to trace stuff in the code in case of error. For example, sometimes I visit a page and I got a blank response with no error messages whatsoever. How should I go about debugging this? Any tools that will be helpful?

My experience has been mainly in C/C++, Perl and some CGI programming. So PHP is a very refreshing experience with me :-)

In case it matters, the application I'm playing with is Lyceum, and I don't have much choice on the LAMP environment itself.

EDIT: Free software tools preferred :-)

Answer 1

I assume your hosting provider configured their PHP installation with display_errors turned off, which is a good thing. That's why you're seeing blank pages. So the most practical solution at the moment would be to have an .htaccess file which turns it on:

php_flag display_errors on

You'd also need error_reporting to an appropriate value:

php_flag error_reporting "E_ALL | E_STRICT"

Anyway, remember to turn this off before letting users access your web site.

For advance debugging I'd recommend Xdebug installed on the server with Eclipse PDT or NetBeans IDE with PHP support as your editor. They both are good clients for debugging, but I really doubt any provider would install Xdebug on their live servers. So you're pretty much left with logging functions if you don't have a development environment.