Xdebug

Xdebug is a php debugger. It allows a developer to debug php applications in a similar manner to that of other languages. Clients can connect to xdebug remotely. NetBeans is an example of a remote client.

• first install apache2, and php
  • ( php will need built WITH cli for command line testing, so don't use --disable-cli flag)
• download source from http://www.xdebug.org
• make sure to install the xt.vim file and configure your filetypes as per the xdebug documentation, to gain syntax highlighting and folding in Vim
• view README to see if process has changed
• in the root of the extracted files…

  phpize
  
  ./configure --enable-xdebug
  
  make
  
  sudo cp modules/xdebug.so /usr/local/apache2/modules/
  
  sudo chown www:www /usr/local/apache2/modules/xdebug.so

• edit php.ini (if php was built as shown on this wiki, edit or create php.ini in /usr/local/lib)

  ; set up xdebug
  zend_extension="/usr/local/apache2/modules/xdebug.so"
  xdebug.remote_enable=1
  xdebug.trace_enable_triger=1
  xdebug.trace_output_dir="/tmp"
  xdebug.trace_output_name="trace.%R"
  xdebug.profiler_enable_triger=1
  xdebug.profiler_output_dir="/tmp"
  xdebug.profiler_output_name="cachegrind.out.%R"
  ;xdebug.remote_handler=dbgp
  ;xdebug.remote_host=localhost
  ;xdebug.remote_port=9000

• restart apache: sudo /usr/local/apache2/bin/apachectl -k graceful
• view a phpinfo() page to verify that the xdebug module is loaded
• for typical debugging, you probably want to get helper extensions in Chrome or Firefox which easily set cookies appropriately for debugging, profiling, and tracing; then connect with something like Vdebug for Vim, or with Netbeans
• for a simple function call dump in php, use one of these lines:

  // make sure the web server can write to this directory, or the
  // file won't show up!!
  xdebug_start_trace(getcwd() . "/trace", XDEBUG_TRACE_APPEND);
  xdebug_start_trace(getcwd() . "/trace");

• other settings for function dumps can be tweaked to show passed parameters, return values, etc…

  ini_set("xdebug.collect_params", 3);
  xdebug.collect_includes = On
  ini_set("xdebug.collect_return", 1);
  xdebug.show_mem_delta = On

• to debug from command line, start a debugging listener client such as Netbeans or XDebugClient and run like this:

  php -dxdebug.remote_autostart=On myprogram.php

• Be sure to download Xdebug Helper extension (Chrome), or The easiest Xdebug (Firefox). You then start a listening client and refresh any php page on a server with xdebug installed.
• for more information, see NetBeans or other client documentation on how to debug

xdebug overloads several php functions, so they don't work exactly as they did before.

• var_dump is limited in certain ways by default; one of these items is the maximum children that can be displayed before you get the message “more elements…”; to fix this, set this parameter:

  ini_set("xdebug.var_display_max_children", -1);