Loading xdebug via -z argument

Question

According to the PHP manpage, the following command line options exist:

  --zend-extension file
   -z file        Load Zend extension file

Which presumably means you can load xdebug as a zend extension this way, thereby only loading Xdebug when you actually need it, which in my case is helpful since xdebug can severely slow down Drupal unit tests, but I may need to debug some tests.

However, loading Xdebug this way does not seem to work.

Environment: MacOS 10.10, PHP 5.6.3-dev, Xdebug 2.2.5.

$> ls -l /usr/local/lib/php/extensions/debug-non-zts-20131226/xdebug.so
-rwxr-xr-x  1 root  wheel  319276 Oct 24 13:45 /usr/local/lib/php/extensions/debug-non-zts-20131226/xdebug.so
$> grep xdebug /usr/local/etc/php/5.6/php.ini
zend_extension=/usr/local/lib/php/extensions/debug-non-zts-20131226/xdebug.so
$> php -v |grep -i xdebug
    with Xdebug v2.2.5, Copyright (c) 2002-2014, by Derick Rethans

So clearly when specified in the php.ini file, xdebug loads correctly. When I comment out the xdebug line,

> grep xdebug /usr/local/etc/php/5.6/php.ini
;zend_extension=/usr/local/lib/php/extensions/debug-non-zts-20131226/xdebug.so

You can see that it's correctly not loaded:

> php -i|grep -i xdebug
>

However, when I try using -z to load the extension,

> php -z /usr/local/lib/php/extensions/debug-non-zts-20131226/xdebug.so -i|grep -i xdebug
> 

And no Xdebug functionality is enabled.

I haven't read anything that mentions that this doesn't work, but it doesn't. While failing to load xdebug via -z doesn't completely preclude me from writing a script to toggle the zend_extension line in the php.ini file, it's not exactly convenient.

Can anybody explain why this is?

Answer 1

I have no explanation of why it does not work with the -z argument, but give this a try:

php -dzend_extension=/usr/local/lib/php/extensions/debug-non-zts-20131226/xdebug.so -f myscript.php

You can then create a shortcut script to profile PHP scripts on the fly. Consider this bash script:

#!/bin/bash

php -dzend_extension=/path/to/xdebug.so -dxdebug.profiler_enable=1 -dxdebug.profiler_output_dir=$(pwd) $@

You're then able to profile a script by using ./xdebug -f script.php, assuming xdebug is the name of your script.