Installation
This section describes on how to install Xdebug.
How you install Xdebug depends on your system. There are the following possibilities:
- Linux with a package manager such
as
apt
,yum
, or something else. - Linux without an Xdebug package with PECL.
- macOSX with homebrew, through PECL.
- Windows, with help from a wizard.
- Unix-like operating systems, from source.
Installing on Linux
Installing Xdebug with a package manager is often the fastest way. Depending on your distribution, run the following command:
- Alpinelinux:
sudo apk add php7-pecl-xdebug
- Arch Linux:
sudo pacman -Sy xdebug
- CentOS:
sudo yum install php-xdebug
- CentOS (Remi Repro):
sudo yum install php74-php-xdebug
- Debian (9/stretch, testing/buster/bullseye/sid):
sudo apt-get install php-xdebug
- Fedora (32):
sudo yum install php-xdebug
- Fedora (Remi Repro):
sudo yum install php74-php-xdebug
- Gentoo:
emerge dev-php/xdebug
- Manjaro (20.1/Mikah):
sudo pacman -S xdebug
- RHEL:
sudo yum install php-xdebug
- RHEL (Remi Repro):
sudo yum install php74-php-xdebug
- SUSE (openSUSE, Enterprise):
sudo zypper in php7-xdebug
- Ubuntu (18.04 LTS/Bionic, 20.04 LTS/Focal):
sudo apt-get install php-xdebug
- Ubuntu (Ondřej Surý's PPA):
sudo apt-get install php7.4-xdebug
Linux distributions might be providing an old and/or outdated version. If the package manager installs a version that is no longer supported (see Supported Versions), please install Xdebug with PECL, or from source instead.
Xdebug's latest version is 3.0.2.
Installing with PECL
You can install Xdebug through PECL on Linux & macOS with Homebrew. Run:
pecl install xdebug
Warning: You should ignore any prompts to add
"extension=xdebug.so"
to
php.ini
— this will cause problems.
In some cases pecl
will change the php.ini
file to
add a configuration line to load Xdebug. You can check whether it did by
running php -v
. If Xdebug shows up with a version number, than
you're all set and you can configure Xdebug's other functions, such as
Step Debugging, or Profiling.
If pecl
did not add the right line, skip to the Configure PHP section.
1 On macOS, you should have PHP installed with Homebrew.
Installing on Windows
There are a few precompiled modules for Windows, they are all for the non-debug version of PHP. You can get those at the download page. Follow these instructions to get Xdebug installed.
Installation From Source
Obtain
You can download the source of the latest stable release 3.0.2.
Alternatively you can obtain Xdebug from GIT:
git clone git://github.com/xdebug/xdebug.git
This will checkout the latest development version which is currently 3.1.0-dev. This development branch might not always work as expected, and may have bugs.
You can also browse the source on GitHub at https://github.com/xdebug/xdebug.
Compile
There is a wizard available that provides you with the correct file to download, and which paths to use.
You compile Xdebug separately from the rest of PHP. You need access to the
scripts phpize
and php-config
. If your system
does not have phpize
and php-config
, you will
need to install the PHP development headers.
Debian users can do that with:
apt-get install php-dev
And RedHat and Fedora users with:
yum install php-devel
It is important that the source version matches the installed version as there
are slight, but important, differences between PHP versions. Once you have
access to phpize
and php-config
, take the
following steps:
Unpack the tarball:
tar -xzf xdebug-3.0.2.tgz
You should not unpack the tarball inside the PHP source code tree. Xdebug is compiled separately, all by itself, as stated above.
cd xdebug-3.0.2
phpize
If phpize is not in your path, please make sure that it is by expanding the
PATH
environment variable. Make sure you use the phpize that belongs to the PHP version that you want to use Xdebug with. See this FAQ entry if you're having some issues with finding which phpize to use../configure --enable-xdebug
make
make install
Configure PHP
Add the following line to
php.ini
:zend_extension=/wherever/you/put/it/xdebug
To find out which
php.ini
file to modify, run a script with the following:<?php var_dump(php_ini_loaded_file(), php_ini_scanned_files());
Alternatively, you can run
php --ini
on the command line.Note: There could be more than one
php.ini
file. In many set-ups there is a different one for the command line (oftencli/php.ini
) and the web server (oftenfpm/php.ini
).Note: If you want to use Xdebug and OPCache together, you must have the
zend_extension
line for Xdebug below the line for OPCache. Otherwise, they won't work properly together.Restart your webserver, or PHP-FPM, depending on what you are using.
Verify that Xdebug is now loaded.
Create a PHP page that calls xdebug_info(). If you request the page through the browser, it should show you an overview of Xdebug's settings and log messages.
On the command line, you can also run
php -v
. Xdebug and its version number should be present as in:PHP 7.4.10 (cli) (built: Aug 18 2020 09:37:14) ( NTS DEBUG ) Copyright (c) The PHP Group Zend Engine v3.4.0, Copyright (c) Zend Technologies with Zend OPcache v7.4.10-dev, Copyright (c), by Zend Technologies with Xdebug v3.0.0-dev, Copyright (c) 2002-2020, by Derick Rethans
With Xdebug loaded, you can now enable individual features, such as Step Debugging, or Profiling.
Related Settings and Functions
- string xdebug.log =
- integer xdebug.log_level = 7
- string xdebug.mode = develop
- xdebug_info() : void
Settings
string xdebug.log = #
Configures Xdebug's log file.
Xdebug will log to this file all file creations issues, Step Debugging connection attempts, failures, and debug communication.
Enable this functionality by setting the value to a absolute path. Make sure
that the system user that PHP runs at (such as www-data
if you are
running with Apache) can create and write to the file.
The file is opened in append-mode, and will therefore not be overwritten by default. There is no concurrency protection available.
The log file will include any attempt that Xdebug makes to connect to an IDE:
[2693358] Log opened at 2020-09-02 07:19:09.616195 [2693358] [Step Debug] INFO: Connecting to configured address/port: localhost:9003. [2693358] [Step Debug] ERR: Could not connect to debugging client. Tried: localhost:9003 (through xdebug.client_host/xdebug.client_port) :-( [2693358] [Profiler] ERR: File '/foo/cachegrind.out.2693358' could not be opened. [2693358] [Profiler] WARN: /foo: No such file or directory [2693358] [Tracing] ERR: File '/foo/trace.1485761369' could not be opened. [2693358] [Tracing] WARN: /foo: No such file or directory [2693358] Log closed at 2020-09-02 07:19:09.617510
It includes the opening time (2020-09-02 07:19:09.616195
), the
IP/Hostname and port Xdebug is trying to connect to
(localhost:9003
), and whether it succeeded (Connected to
client :-)
). The number in brackets ([2693358]
) is the
Process ID.
It includes:
[2693358]
- process ID in brackets
2020-09-02 07:19:09.616195
- opening time
For Step Debugging:
INFO: Connecting to configured address/port: localhost:9003. ERR: Could not connect to debugging client. Tried: localhost:9003 (through xdebug.client_host/xdebug.client_port) :-(
For Profiling:
ERR: File '/foo/cachegrind.out.2693358' could not be opened. WARN: /foo: No such file or directory
For Function Trace:
ERR: File '/foo/trace.1485761369' could not be opened. WARN: /foo: No such file or directory
All warnings and errors are described on the Description of errors page, with
detailed instructions on how to resolve the problem, if possible. All errors are always logged through
PHP's internal logging mechanism (configured with error_log
in php.ini
). All warnings and errors also show up in the
diagnostics log that you can view by calling xdebug_info().
Step Debugger Communication
The debugging log can also log the communication between Xdebug and an IDE.
This communication is in XML, and starts with the <init
XML
element:
<init xmlns="urn:debugger_protocol_v1" xmlns:xdebug="https://xdebug.org/dbgp/xdebug" fileuri="file:///home/httpd/www.xdebug.org/html/router.php" language="PHP" xdebug:language_version="7.4.11-dev" protocol_version="1.0" appid="2693358" idekey="XDEBUG_ECLIPSE"> <engine version="3.0.0-dev"><![CDATA[Xdebug]]></engine> <author><![CDATA[Derick Rethans]]></author> <url><![CDATA[https://xdebug.org]]></url> <copyright><![CDATA[Copyright (c) 2002-2020 by Derick Rethans]]></copyright> </init>
The fileuri
attribute lists the entry point of your
application, which can be useful to compare to breakpoint_set
commands to see if path mappings are set-up correctly.
Beyond the <init
element, you will find the configuration of
features:
<- feature_set -i 4 -n extended_properties -v 1 -> <response xmlns="urn:debugger_protocol_v1" xmlns:xdebug="https://xdebug.org/dbgp/xdebug" command="feature_set" transaction_id="4" feature="extended_properties" success="1"> </response>
<- step_into -i 9 -> <response xmlns="urn:debugger_protocol_v1" xmlns:xdebug="https://xdebug.org/dbgp/xdebug" command="step_into" transaction_id="9" status="break" reason="ok"> <xdebug:message filename="file:///home/httpd/www.xdebug.org/html/router.php" lineno="3"> </xdebug:message> </response>
You can read about DBGP - A common debugger protocol specification at its dedicated documation page.
The xdebug.log_level setting controls how much information is logged.
Note: Many Linux distributions now use systemd, which
implements private tmp directories. This means that when PHP
is run through a web server or as PHP-FPM, the /tmp
directory is
prefixed with something akin to:
/tmp/systemd-private-ea3cfa882b4e478993e1994033fc5feb-apache.service-FfWZRg
This setting can additionally be configured through the
XDEBUG_CONFIG
environment variable.
integer xdebug.log_level = 7 #
Configures which logging messages should be added to the log file.
The log file is configured with the xdebug.log setting.
The following levels are supported:
Level | Name | Example |
---|---|---|
0 | Criticals | Errors in the configuration |
1 | Errors | Connection errors |
3 | Warnings | Connection warnings |
5 | Communication | Protocol messages |
7 | Information | Information while connecting |
10 | Debug | Breakpoint resolving information |
Criticals, errors, and warnings always show up in the diagnostics log that you can view by calling xdebug_info().
Criticals and errors are additionally logged through
PHP's internal logging mechanism (configured with error_log
in php.ini
).
This setting can additionally be configured through the
XDEBUG_CONFIG
environment variable.
string xdebug.mode = develop #
This setting controls which Xdebug features are enabled.
This setting can only be set in php.ini
or
files like 99-xdebug.ini
that are read when a PHP process starts
(directly, or through php-fpm), but not in .htaccess
and
.user.ini
files where are read per-request.
The following values are accepted:
off
- Nothing is enabled. Xdebug does no work besides checking whether functionality is enabled. Use this setting if you want close to 0 overhead.
develop
- Enables Development Aids including the overloaded var_dump().
coverage
- Enables Code Coverage Analysis to generate code coverage reports, mainly in combination with PHPUnit.
debug
- Enables Step Debugging. This can be used to step through your code while it is running, and analyse values of variables.
gcstats
- Enables Garbage Collection Statistics to collect statistics about PHP's Garbage Collection Mechanism.
profile
- Enables Profiling, with which you can analyse performance bottlenecks with tools like KCacheGrind.
trace
- Enables the Function Trace feature, which allows you record every function call, including arguments, variable assignment, and return value that is made during a request to a file.
You can enable multiple modes at the same time by comma separating their
identifiers as value to xdebug.mode: xdebug.mode=develop,trace
.
You can also set the mode by setting the XDEBUG_MODE
environment
variable on the command-line; this will take precedence over the xdebug.mode
setting.
Functions
xdebug_info() : void #
Show diagnostic information
This function returns an HTML page which shows diagnostic information. It is analogous to PHP's phpinfo() function.
The HTML output includes which mode is active, what the settings are, and diagnostic information in case there are problems with debugging connections, opening of files, etc.
Each warning and error in the diagnostics log also links through to the Description of errors documentation page.