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= Generating a Backtrace =

== If you don't have a core file yet ==
Read [http://bugs.php.net/bugs-generating-backtrace.php generating a Backtrace] on php.net.
  * config xcache.coredump_directory in /etc/php.ini, For apache + mod_php, you have [http://httpd.apache.org/docs/2.0/mod/mpm_common.html#coredumpdirectory CoreDumpDirectory] in apache.conf
  * Ensure that the xcache.coredump_directory has write permissions for the user who's running PHP
  * Remove any limits you may have on core dump size from your shell:
    * tcsh: unlimit coredumpsize
    * bash/sh: ulimit -c unlimited
  * Cause PHP to crash:
    * PHP CGI: Simply run php with the script that crashes it
    * PHP FastCGI: Simply setup normal webserver-fastcgi configuration, and access the script that crashes PHP
    * PHP As Apache Module: Run httpd -X, and access the script that crashes PHP
== Once you have the core file ==
First, check where the coredump is
====== Checking where the coredump is ======
{{{
#!ShellExample
$ grep xcache.coredump_directory /etc/php.ini
xcache.coredump_directory = "/tmp/"
$ ls /tmp/core
/tmp/core
}}}

 * PHP as CGI/FastCGI: Run gdb with the path to the PHP or PHP-enabled httpd binary, and path to the core file, for example:
====== Generating backtrace for PHP as CGI/FastCGI ======
{{{
#!ShellExample
$ gdb /usr/local/bin/php-cgi-fcgi /tmp/core
........
(gdb) bt
(gdb) source ~/src/php5/.gdbinit
(gdb) dump_bt executor_globals.current_execute_data
}}}

  * PHP As Webserver Module: Run gdb with the path to the PHP or PHP-enabled httpd binary, and path to the core file, for example:
====== Generating backtrace for PHP as As Webserver Module ======
{{{
#!ShellExample
$ gdb /usr/local/apache/sbin/httpd /tmp/core
........
(gdb) bt
(gdb) source ~/src/php5/.gdbinit
(gdb) dump_bt executor_globals.current_execute_data
}}}