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Documentation - all settings

This section describes all available configuration settings available in Xdebug.


integer xdebug.cli_color = 0 #

If this setting is 1, Xdebug will color var_dumps and stack traces output when in CLI mode and when the output is a tty. On Windows, the ANSICON tool needs to be installed.

If the setting is 2, then Xdebug will always color var_dumps and stack trace, no matter whether it's connected to a tty or whether ANSICON is installed. In this case, you might end up seeing escape codes.

See this article for some more information.


string xdebug.client_host = localhost #

Configures the IP address or hostname where Xdebug will attempt to connect to when initiating a debugging connection. This address should be the address of the machine where your IDE or debugging client is listening for incoming debugging connections.

On non-Windows platforms, it is also possible to configure a Unix domain socket which is supported by only a select view debugging clients. In that case, instead of the hostname or IP address, use unix:///path/to/sock.

If xdebug.remote_connect_back is enabled then Xdebug will only use the value of this setting in case Xdebug can not connect to an IDE using the information it obtained from HTTP headers. In that case, the value of this setting acts as a fallback only.


integer xdebug.client_port = 9000 #

The port to which Xdebug tries to connect on the remote host. Port 9003 is the default for both Xdebug and the Command Line Debug Client. As many clients use this port number, it is best to leave this setting unchanged.


boolean xdebug.collect_assignments = false #

This setting, defaulting to 0, controls whether Xdebug should add variable assignments to function traces. Assign-by-var (=&) assignments are included too.


integer xdebug.collect_params = 0 #

This setting, defaulting to 0, controls whether Xdebug should collect the parameters passed to functions when a function call is recorded in either the function trace or the stack trace.

The setting defaults to 0 because for very large scripts it may use huge amounts of memory and therefore make it impossible for the huge script to run. You can most safely turn this setting on, but you can expect some problems in scripts with a lot of function calls and/or huge data structures as parameters. Xdebug 2 will not have this problem with increased memory usage, as it will never store this information in memory. Instead it will only be written to disk. This means that you need to have a look at the disk usage though.

This setting can have four different values. For each of the values a different amount of information is shown. Below you will see what information each of the values provides. See also the introduction of the feature Development Aids for a few screenshots.

ValueArgument Information Shown
0None.
1Type and number of elements (f.e. string(6), array(8)).
2

Type and number of elements, with a tool tip for the full information 1.

3Full variable contents (with the limits respected as set by xdebug.var_display_max_children, xdebug.var_display_max_data and xdebug.var_display_max_depth.
4Full variable contents and variable name.
5PHP serialized variable contents, without the name.

1 in the CLI version of PHP it will not have the tool tip, nor in output files.


boolean xdebug.collect_return = false #

This setting, defaulting to 0, controls whether Xdebug should write the return value of function calls to the trace files.


integer xdebug.connect_timeout_ms = 200 #

The amount of time in milliseconds that Xdebug will wait for on an IDE to acknowledge an incoming debugging connection. The default value of 200 ms should in most cases be enough. In case you often get dropped debugging requests, perhaps because you have a high latency network, or a development box far away from your IDE, or have a slow firewall, then you can should increase this value.

Please note that increasing this value might mean that your requests seem to 'hang' in case Xdebug tries to establish a connection, but your IDE is not listening.


string xdebug.dump.* = Empty #

* can be any of COOKIE, FILES, GET, POST, REQUEST, SERVER, SESSION. These seven settings control which data from the superglobals is shown when an error situation occurs.

Each of those php.ini setting can consist of a comma seperated list of variables from this superglobal to dump, or * for all of them. Make sure you do not add spaces in this setting.

In order to dump the REMOTE_ADDR and the REQUEST_METHOD when an error occurs, and all GET parameters, add these settings:

xdebug.dump.SERVER = REMOTE_ADDR,REQUEST_METHOD
xdebug.dump.GET = *

boolean xdebug.dump_globals = true #

When this setting is set to true, Xdebug adds the values of the super globals as configured through the xdebug.dump.* to on-screen stack traces and the error log (if enabled).


boolean xdebug.dump_once = true #

Controls whether the values of the superglobals should be dumped on all error situations (set to 0) or only on the first (set to 1).


boolean xdebug.dump_undefined = false #

If you want to dump undefined values from the superglobals you should set this setting to 1, otherwise leave it set to 0.


string xdebug.file_link_format = #

This setting determines the format of the links that are made in the display of stack traces where file names are used. This allows IDEs to set up a link-protocol that makes it possible to go directly to a line and file by clicking on the filenames that Xdebug shows in stack traces. An example format might look like:

myide://%f@%l

The possible format specifiers are:

SpecifierMeaning
%fthe filename
%lthe line number

For various IDEs/OSses there are some instructions listed on how to make this work:

Firefox on Linux

  • Open about:config
  • Add a new boolean setting "network.protocol-handler.expose.xdebug" and set it to "false"
  • Add the following into a shell script ~/bin/ff-xdebug.sh:
    #! /bin/sh
    
    f=`echo $1 | cut -d @ -f 1 | sed 's/xdebug:\/\///'`
    l=`echo $1 | cut -d @ -f 2`
    
    Add to that one of (depending whether you have komodo, gvim or netbeans):
    • komodo $f -l $l
    • gvim --remote-tab +$l $f
    • netbeans "$f:$l"
  • Make the script executable with chmod +x ~/bin/ff-xdebug.sh
  • Set the xdebug.file_link_format setting to xdebug://%f@%l

Windows and netbeans

  • Create the file netbeans.bat and save it in your path (C:\Windows will work):
    @echo off
    setlocal enableextensions enabledelayedexpansion
    set NETBEANS=%1
    set FILE=%~2
    %NETBEANS% --nosplash --console suppress --open "%FILE:~19%"
    nircmd win activate process netbeans.exe
    

    Note: Remove the last line if you don't have nircmd.

  • Save the following code as netbeans_protocol.reg:
    Windows Registry Editor Version 5.00
    
    [HKEY_CLASSES_ROOT\netbeans]
    "URL Protocol"=""
    @="URL:Netbeans Protocol"
    
    [HKEY_CLASSES_ROOT\netbeans\DefaultIcon]
    @="\"C:\\Program Files\\NetBeans 7.1.1\\bin\\netbeans.exe,1\""
    
    [HKEY_CLASSES_ROOT\netbeans\shell]
    
    [HKEY_CLASSES_ROOT\netbeans\shell\open]
    
    [HKEY_CLASSES_ROOT\netbeans\shell\open\command]
    @="\"C:\\Windows\\netbeans.bat\" \"C:\\Program Files\\NetBeans 7.1.1\\bin\\netbeans.exe\" \"%1\""
    

    Note: Make sure to change the path to Netbeans (twice), as well as the netbeans.bat batch file if you saved it somewhere else than C:\Windows\.

  • Double click on the netbeans_protocol.reg file to import it into the registry.
  • Set the xdebug.file_link_format setting to xdebug.file_link_format = "netbeans://open/?f=%f:%l"

string xdebug.filename_format = ...%s%n #

This setting determines the format with which Xdebug renders filenames in HTML stack traces (default: ...%s%n) and location information through the overloaded xdebug_var_dump() (default: %f).

The possible format specifiers are listed in this table. The example output is rendered according to the full path /var/www/vendor/mail/transport/mta.php.

SpecifierMeaningExample Output
%aAncester: Two directory elements and filenamemail/transport/mta.php
%fFull path/var/www/vendor/mail/transport/mta.php
%nName: Only the file namemta.php
%pParent: One directory element and the filenametransport/mta.php
%sDirectory separator/ on Linux, OSX and other Unix-like systems, \ on Windows

integer xdebug.force_display_errors = 0 #

If this setting is set to 1 then errors will always be displayed, no matter what the setting of PHP's display_errors is.


integer xdebug.force_error_reporting = 0 #

This setting is a bitmask, like error_reporting. This bitmask will be logically ORed with the bitmask represented by error_reporting to dermine which errors should be displayed. This setting can only be made in php.ini and allows you to force certain errors from being shown no matter what an application does with ini_set().


string xdebug.gc_stats_output_name = gcstats.%p #

This setting determines the name of the file that is used to dump garbage collection statistics into. The setting specifies the format with format specifiers, very similar to sprintf() and strftime(). There are several format specifiers that can be used to format the file name.

See the xdebug.trace_output_name documentation for the supported specifiers.


integer xdebug.halt_level = 0 #

This setting allows you to configure a mask that determines whether, and which, notices and/or warnings get converted to errors. You can configure notices and warnings that are generated by PHP, and notices and warnings that you generate yourself (by means of trigger_error()). For example, to convert the warning of strlen() (without arguments) to an error, you would do:

ini_set('xdebug.halt_level', E_WARNING);
strlen();
echo "Hi!\n";

Which will then result in the showing of the error message, and the abortion of the script. echo "Hi!\n"; will not be executed.

The setting is a bit mask, so to convert all notices and warnings into errors for all applications, you can set this in php.ini:

xdebug.halt_level=E_WARNING|E_NOTICE|E_USER_WARNING|E_USER_NOTICE

The bitmask only supports the four level that are mentioned above.


string xdebug.idekey = *complex* #

Controls which IDE Key Xdebug should pass on to the debugging client or proxy. The IDE Key is only important for use with the DBGp Proxy Tool, although some IDEs are incorrectly picky as to what its value is.

The default is based on the DBGP_IDEKEY environment setting. If it is not present, the default falls back to an empty string.

If this setting is set to a non-empty string, it selects its value over DBGP_IDEKEY environment variable as default value.

The internal IDE Key also gets updated through debugging session management and overrides the value of this setting as is explained in the Step Debugging documentation.


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:

[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>

And continuation commands:

<- 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

integer xdebug.log_level = 7 #

Configures which logging messages should be emitted.

The following levels are supported:

LevelNameExample
1ErrorsConnection errors
3WarningsConnection warnings
5CommunicationProtocol messages
7InformationInformation while connecting
10DebugBreakpoint resolving information

Errors are also logged through PHP's internal logging mechanism (configured with error_log in php.ini).

Warnings and errors show up in the diagnostics log that you can view by calling xdebug_info().


integer xdebug.max_nesting_level = 256 #

Controls the protection mechanism for infinite recursion protection. The value of this setting is the maximum level of nested functions that are allowed before the script will be aborted.

When the maximum nesting level is reached, an "Error" exception is thrown.


integer xdebug.max_stack_frames = -1 #

Controls how many stack frames are shown in stack traces, both on the command line during PHP error stack traces, as well as in the browser for HTML traces.


string xdebug.mode = display #

This setting controls which Xdebug features are enabled.

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.

string xdebug.output_dir = /tmp #

The directory where Xdebug will write tracing, profiling, and garbage collection statistics to. This directory needs to be writable for the system user with which PHP is running.

This setting can be changed in php.ini, .htaccess (and equivalent files), and within a PHP file with ini_set().

In some cases (when profiling, or when xdebug.start_with_request=yes with tracing), Xdebug creates the file before the script runs. In that case, changes made through ini_set() will not be taken into account.


integer xdebug.profiler_append = 0 #

When this setting is set to 1, profiler files will not be overwritten when a new request would map to the same file (depending on the xdebug.profiler_output_name setting. Instead the file will be appended to with the new profile.


string xdebug.profiler_output_name = cachegrind.out.%p #

This setting determines the name of the file that is used to dump traces into. The setting specifies the format with format specifiers, very similar to sprintf() and strftime(). There are several format specifiers that can be used to format the file name.

See the xdebug.trace_output_name documentation for the supported specifiers.


string xdebug.remote_addr_header = "" #

If xdebug.remote_addr_header is configured to be a non-empty string, then the value is used as key in the $_SERVER superglobal array to determine which header to use to find the IP address or hostname to use for 'connecting back to'. This setting is only used in combination with xdebug.remote_connect_back and is otherwise ignored.

For example, if xdebug.remote_addr_header is set to FORWARD_HOST, then Xdebug will check $_SERVER['FORWARD_HOST'] before the $_SERVER['HTTP_X_FORWARDED_FOR'] and $_SERVER['REMOTE_ADDR'] variables.


boolean xdebug.remote_connect_back = false #

If enabled, Xdebug will first try to connect to the client that made the HTTP request. It checks the $_SERVER['HTTP_X_FORWARDED_FOR'] and $_SERVER['REMOTE_ADDR'] variables to find out which hostname or IP address to use.

If xdebug.remote_addr_header is configured, then the $_SERVER variable with that configured name will be checked before HTTP_X_FORWARDED_FOR and REMOTE_ADDR.

If Xdebug can not connect to a debugging client as found in one of the HTTP headers, it will fall back to the hostname or IP address as configured by the xdebug.client_host setting.

This setting does not apply for debugging through the CLI, as the $_SERVER header variables are not available there.

Warning: Please note that there is no filter available, and anybody who can connect to the webserver will then be able to start a debugging session, even if their address does not match xdebug.client_host.


boolean xdebug.scream = false #

If this setting is 1, then Xdebug will disable the @ (shut-up) operator so that notices, warnings and errors are no longer hidden.


integer xdebug.show_error_trace = 0 #

When this setting is set to 1, Xdebug will show a stack trace whenever an Error is raised - even if this Error is actually caught.


integer xdebug.show_exception_trace = 0 #

When this setting is set to 1, Xdebug will show a stack trace whenever an Exception or Error is raised - even if this Exception or Error is actually caught.

Error 'exceptions' were introduced in PHP 7.


integer xdebug.show_local_vars = 0 #

When this setting is set to something != 0 Xdebug's generated stack dumps in error situations will also show all variables in the top-most scope. Beware that this might generate a lot of information, and is therefore turned off by default.


string xdebug.start_upon_error = default #

Step Debugging can be activated when a PHP Notice or Warning is emitted, or when a Throwable (Exception/Error) is thrown, depending on the value of this setting:

yes

Initialise a debugging session when a PHP Notice or Warning is emitted, or when a Throwable is thrown.

no
default

Do not start a debugging session upon an error situation.

This setting is independent of xdebug.start_with_request, and therefore it is not necessary to set xdebug.start_with_request=trigger.


string xdebug.start_with_request = default #

A Function Trace, Garbage Collection Statistics, Profiling, or Step Debugging can be activated at the start of a PHP request. Whether this happens depends on the value of this setting:

yes

The functionality starts when the PHP request starts, and before any PHP code is run.

For example xdebug.mode=trace and xdebug.start_with_request=yes starts a Function Trace for the whole request.

no

The functionality does not get activated when the request starts.

You can still start a Function Trace with xdebug_start_trace(), Step Debugging with xdebug_break(), or Garbage Collection Statistics with xdebug_start_gcstats().

trigger

The functionality only gets activated when a specific trigger is present when the request starts.

The name of the trigger is XDEBUG_TRIGGER, and Xdebug checks for its presence in either $_ENV (environment variable), $_GET or $_POST variable, or $_COOKIE (HTTP cookie name).

There is also a legacy fallback to a functionality specific trigger name: XDEBUG_PROFILE (for Profiling), XDEBUG_TRACE (for a Function Trace), and XDEBUG_SESSION (for Step Debugging).

Debug session management for Step Debugging is also still available through XDEBUG_SESSION_START.

With xdebug.trigger_value you can control which specific trigger value will activate the trigger. If xdebug.trigger_value is set to an empty string, any value will be accepted.

default

The default value depends on xdebug.mode:

  • debug: trigger

  • gcstats: no

  • profile: yes

  • trace: trigger


integer xdebug.trace_format = 0 #

The format of the trace file.

ValueDescription
0shows a human readable indented trace file with: time index, memory usage, memory delta (if the setting xdebug.show_mem_delta is enabled), level, function name, function parameters (if the setting xdebug.collect_params is enabled), filename and line number.
1writes a computer readable format which has two different records. There are different records for entering a stack frame, and leaving a stack frame. The table below lists the fields in each type of record. Fields are tab separated.
2writes a trace formatted in (simple) HTML.

Fields for the computerized format:

Record type123456789101112 - ...
Entry level function # always '0' time index memory usage function name user-defined (1) or internal function (0) name of the include or require file filename line number no. of arguments arguments (as many as specified in field 11) - tab separated
Exit level function # always '1' time index memory usage empty
Return level function # always 'R' empty return value empty

See the introduction for Function Trace for a few examples.


integer xdebug.trace_options = 0 #

When set to '1' the trace files will be appended to, instead of being overwritten in subsequent requests.


string xdebug.trace_output_name = trace.%c #

This setting determines the name of the file that is used to dump traces into. The setting specifies the format with format specifiers, very similar to sprintf() and strftime(). There are several format specifiers that can be used to format the file name. The '.xt' extension is always added automatically.

The possible format specifiers are:

SpecifierMeaningExample FormatExample Filename
%ccrc32 of the current working directorytrace.%ctrace.1258863198.xt
%ppidtrace.%ptrace.5174.xt
%rrandom numbertrace.%rtrace.072db0.xt
%s

script name 2

cachegrind.out.%scachegrind.out._home_httpd_html_test_xdebug_test_php
%ttimestamp (seconds)trace.%ttrace.1179434742.xt
%utimestamp (microseconds)trace.%utrace.1179434749_642382.xt
%H$_SERVER['HTTP_HOST']trace.%Htrace.kossu.xt
%R$_SERVER['REQUEST_URI']trace.%Rtrace._test_xdebug_test_php_var=1_var2=2.xt
%U$_SERVER['UNIQUE_ID'] 3trace.%Utrace.TRX4n38AAAEAAB9gBFkAAAAB.xt
%Ssession_id (from $_COOKIE if set)trace.%Strace.c70c1ec2375af58f74b390bbdd2a679d.xt
%%literal %trace.%%trace.%%.xt

2 This one is only available for trace file names since Xdebug 2.6.

3 New in version 2.2. This one is set by Apache's mod_unique_id module


string xdebug.trigger_value = "" #

This setting can be used when xdebug.start_with_request is set to trigger, which is the default for Step Debugging and Function Trace.

In trigger mode, Xdebug will only start its functionality when the XDEBUG_TRIGGER is set in the environment, or when the XDEBUG_TRIGGER GET, POST, or COOKIE variable is set.

Normally, Xdebug does not look at which value is actually used. If this setting is set to a non-empty string, then Xdebug will only trigger if the value matches the value of this setting.

With the following settings:

xdebug.mode=profile
xdebug.start_with_request=trigger
xdebug.trigger_value=StartProfileForMe

Xdebug's profiler will only start when either the environment variable XDEBUG_TRIGGER is set to StartProfileForMe, the GET or POST variable XDEBUG_TRIGGER is set to StartProfileForMe, or when the cookie XDEBUG_TRIGGER has the value StartProfileForMe.

See also:

xdebug.start_with_request#trigger
For how the triggering mechanism works, and which environment and server variables Xdebug acts on.

integer xdebug.var_display_max_children = 128 #

Controls the amount of array children and object's properties are shown when variables are displayed with either xdebug_var_dump(), xdebug.show_local_vars or when making a Function Trace.

To disable any limitation, use -1 as value.

This setting does not have any influence on the number of children that is send to the client through the Step Debugging feature.


integer xdebug.var_display_max_data = 512 #

Controls the maximum string length that is shown when variables are displayed with either xdebug_var_dump(), xdebug.show_local_vars or when making a Function Trace.

To disable any limitation, use -1 as value.

This setting does not have any influence on the number of children that is send to the client through the Step Debugging feature.


integer xdebug.var_display_max_depth = 3 #

Controls how many nested levels of array elements and object properties are when variables are displayed with either xdebug_var_dump(), xdebug.show_local_vars or when making a Function Trace.

The maximum value you can select is 1023. You can also use -1 as value to select this maximum number.

This setting does not have any influence on the number of children that is send to the client through the Step Debugging feature.