Xdebug

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Xdebug is a debugging tool for PHP. It provides step-debugging and a whole
range of development aids, such as stack traces, a code profiler, features to
dump the full execution of your script to a file, and more.

Requirements

Xdebug requires a supported <https://php.net/support>_ version of PHP. For
installation it requires the pecl tool (available through the php-pear
package), unless your Linux distribution has an Xdebug package (php-xdebug).

Installation

On most Linux distributions you can install Xdebug through its package
manager. You can also compile from source with the pecl tool through pecl install xdebug. The latter also works for MacOS as long as PHP is installed
with Homebrew.

On Windows, you need to download <https://xdebug.org/download#releases>_ a
binary. Use the Wizard <https://xdebug.org/wizard>_.

Unless you have installed Xdebug with a package manager on Linux, you also
need to add the following line to your php.ini file, or create a new Xdebug
specific ini file xdebug.ini in the conf.d directory. In either case, it
needs the following line added::

zend_extension=xdebug

For more extensive installation instructions, see the documentation at
https://xdebug.org/docs/install

Configuration

Most features in Xdebug have to be opted in into. Each feature has a specific
opt-in. For example to use the step debugger <https://xdebug.org/docs/remote>_ you need to set xdebug.remote_enable=1 in
your configuration file. The step debugger requires an IDE (client), of which
there are many available <https://xdebug.org/docs/remote#clients>_.

The documentation has instructions for each of Xdebug's features:
https://xdebug.org/docs/ and a full list of settings <https://xdebug.org/docs/all_settings>_ is also available there.

Contributing

Xdebug is written in C, and extensive knowledge of PHP's internals is
necessary to be able to contribute. Contributing guidance is available
separately <https://github.com/xdebug/xdebug/blob/master/CONTRIBUTING.rst>_.

Before you begin to contribute, please reach out first. Either through email
(address at the bottom), an issue in the issue tracker <https://bugs.xdebug.org>_ or preferably through IRC on Freenode's #xdebug
channel.

Testing

If you are familiar with compiling PHP extension from source, have a local
checkout of Xdebug's GitHub repository, and have compiled Xdebug in that
directory following the instructions under installation <https://xdebug.org/docs/install#source>_ you can run Xdebug's tests by
running::

php run-xdebug-tests.php

The test framework requires that the PHP binary on the path has Xdebug loaded,
with remote debugging enabled through xdebug.remote_enable=1. It is possible
to skip remote debugging tests by exporting the SKIP_DBGP_TESTS=1 environment
variable.

The SKIP_UNPARALLEL_TESTS=1 can be used to skip tests that can not run in
parallel environments, and the SKIP_SLOW_TESTS=1 environment variable to skip
slow tests. The OPCACHE environment variable can either be yes or no and
controls whether the test framework enables or disables OpCache.

Licensing

Xdebug is released under The Xdebug License <https://github.com/xdebug/xdebug/blob/master/LICENSE>, which is based on
The PHP License <https://github.com/php/php-src/blob/master/LICENSE>. It is
an Open Source license (though not explicitly endorsed by the Open Source
Initiative).

Further Reading

Xdebug has extensive documentation on its website <https://xdebug.org/docs>_.
There are over a hundred settings and many functions documented. Please have a
look through the wealth of information that Xdebug can provide to make your
every day development with PHP easier.

Support

For questions regarding Xdebug, please use StackOverflow <https://stackoverflow.com/questions/tagged/xdebug>_, and tag your question
with xdebug.

You can also find ad-hoc and sporadic support on IRC: freenode/#xdebug.
You can do that with your favourite client, or by using their webchat <http://webchat.freenode.net/?channels=#xdebug>_.

If you think that you encountered a bug, please file a detailed bug report
at https://bugs.xdebug.org. You are required to create an account, this is
so that you can be contacted for additional information and to keep out
spam.

Derick Rethans — derick@xdebug.org