This section describes on how to install Xdebug.
How you install Xdebug depends on your system. There are the following possibilities:
apt, yum, or something else.Installing Xdebug with a package manager is often the fastest way. Depending on your distribution, run the following command:
sudo apk add php7-pecl-xdebugsudo pacman -S xdebugsudo yum install php-xdebugsudo yum install php74-php-xdebug3sudo apt-get install php-xdebugsudo yum install php-xdebugsudo yum install php74-php-xdebug3emerge dev-php/xdebugsudo pacman -S xdebugsudo yum install php-xdebugsudo yum install php74-php-xdebug3sudo zypper in php7-xdebugsudo apt-get install php-xdebugsudo apt-get install php7.4-xdebugXdebug's latest version is 3.1.2.
For packages that have the PHP version in the package name, such as in
php74-php-xdebug3, you can substitute the PHP
version with the one that matches the PHP version that you are running.
Linux distributions might be providing an old and/or outdated version.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.
You can install Xdebug through PECL on Linux & macOS with Homebrew. Run:
pecl install xdebug
On Apple M1 hardware, you might instead need to use:
arch -x86_64 sudo pecl install xdebug
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.
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.
You can download the source of the latest stable release 3.1.2.
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 3.2.0dev. 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.
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-3.1.2.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-3.1.2
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
Find out which PHP ini file to modify.
Run a script with the following to find all configuration files that PHP has loaded:
<?php var_dump(php_ini_loaded_file(), php_ini_scanned_files());
Alternatively, you can run php --ini on the command line.
If there is a file with xdebug in the name, such as
/etc/php/7.4/cli/conf.d/99-xdebug.ini, then this is the
file to use.
If that file does not exist, but there are other files in a
conf.d or similar directory, you can create a new file there too.
Please name it 99-xdebug.ini in that case.
Otherwise, modify the php.ini file that is displayed through
the script, or php --ini command.
There could be more than one
php.ini file. In many set-ups there is a different one for the
command line (often cli/php.ini) and the web server (often
fpm/php.ini).
If you want to use Xdebug and
OPCache together, you must have the zend_extension line for Xdebug
below the line for OPCache, or in a file starting with a higher number (ie.
99-xdebug.ini vs 20-opcache.ini), otherwise they
won't work properly together.
Add the following line to this PHP ini file:
zend_extension=xdebug
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
If Xdebug does not show up, or you get a warning from PHP that an
xdebug.so file or similar was not found, you might need to use the
full path instead of just zend_extension=xdebug, such as
zend_extension=/usr/lib/php/20190902/xdebug.so.
On Windows, you should place the php_xdebug.dll in the
ext/ directory, which is a child directory in your PHP
installation tree.
If you have trouble with this, please refer to the installation wizard to help you guide through this process.
With Xdebug loaded, you can now enable individual features, such as Step Debugging, or Profiling.
Xdebug 3: Diagnostics
This video teaches you how to troubleshoot your Xdebug setup. It explains how to find out how Xdebug is configured, which settings have been made, and what it is attempting to do regarding its different features.
Xdebug 3: Modes
This video introduces Xdebug 3's modes — the new way to configure which parts of Xdebug you have enabled.
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]2020-09-02 07:19:09.616195For 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().
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.
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.
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.
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, which are read per-request.
The following values are accepted:
offdevelopcoveragedebuggcstatsprofiletraceYou 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 Xdebug's mode by setting the XDEBUG_MODE
environment variable on the command-line; this will take precedence over the
xdebug.mode setting, but will not change the value of the xdebug.mode
setting.
Some web servers have a configuration option to
prevent environment variables from being propagated to PHP and Xdebug.
For example, PHP-FPM has a clear_env
configuration setting that is on by default, which you will
need to turn off if you want to use XDEBUG_MODE.
Make sure that your web server does not clean the environment, or specifically
allows the XDEBUG_MODE environment variable to be passed on.
Show and retrieve diagnostic information
This function presents APIs to retrieve information about Xdebug itself. Which information gets returned, or displayed, depends on which arguments, or none at all, are given.
$category = Without arguments, 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.
$category = 'mode' (New in Xdebug 3.1)
The function returns an array of all the
enabled modes, whether through xdebug.mode or the
XDEBUG_MODE environment variable.
<?php
var_dump( xdebug_info( 'mode' ) );
?>
array(3) {
[0] =>
string(5) "debug"
[1] =>
string(7) "develop"
[2] =>
string(5) "trace"
}
$category = 'extension-flags' (New in Xdebug 3.1)
The function returns an array of all the compile flags that were enabled when
running ./configure as part of Xdebug's compilation process.
The only flag that is available, is the compression flag. If this
flag is enabled, then the xdebug.use_compression setting is available, and enabled by default.
Profiling and Function Trace will create GZip compressed files if the xdebug.use_compression setting is turned on (the default).
<?php
var_dump( xdebug_info( 'extension-flags' ) );
?>
array(1) {
[0] =>
string(11) "compression"
}