During debugging, we often need to isolate problem first to make sure if its really PHP problem or Nginx is doing something wrong.
In those cases, cgi-fcgi command might come handy.
Installing cgi-fcgi of Ubuntu
Just run following command:
apt-get install libfcgi0ldbl
Connect to PHP-FPM Directly
Assuming you are running PHP-FPM using TCP/IP with IP and PORT values 127.0.0.1 and 9000 respectively, below are some code sample you may want to execute.
Test PHP-FPM Ping Page
I have posted about this at length here https://rtcamp.com/tutorials/php/fpm-status-page/
You can run following codes from command line to test output:
SCRIPT_NAME=/ping \
SCRIPT_FILENAME=/ping \
REQUEST_METHOD=GET \
cgi-fcgi -bind -connect 127.0.0.1:9000
Above will return output like below:
Content-Type: text/plain
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Cache-Control: no-cache, no-store, must-revalidate, max-age=0
pong
Test PHP-FPM Status Page
I have posted about this at length here https://rtcamp.com/tutorials/php/fpm-status-page/
You can run following codes from command line to test output:
SCRIPT_NAME=/status \
SCRIPT_FILENAME=/status \
REQUEST_METHOD=GET \
cgi-fcgi -bind -connect 127.0.0.1:9000
Above will return output like below:
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Cache-Control: no-cache, no-store, must-revalidate, max-age=0
Content-Type: text/plain
pool: www
process manager: dynamic
start time: 08/Jan/2014:15:04:57 +0530
start since: 93492
accepted conn: 1215
listen queue: 0
max listen queue: 1
listen queue len: 0
idle processes: 26
active processes: 4
total processes: 30
max active processes: 34
max children reached: 0
slow requests: 150
In case you want to test full status page, you can use commands like:
SCRIPT_NAME=/status \
SCRIPT_FILENAME=/status \
QUERY_STRING=full \
REQUEST_METHOD=GET \
cgi-fcgi -bind -connect 127.0.0.1:9000
In case you want to execute custom script, you can specify document root using
SCRIPT_NAME=/custom.php \
SCRIPT_FILENAME=/custom.php \
QUERY_STRING=VAR1 \
DOCUMENT_ROOT=/var/www/example.com/htdocs/ \
REQUEST_METHOD=GET \
cgi-fcgi -bind -connect 127.0.0.1:9000
References: http://www.fastcgi.com/devkit/doc/fcgi-devel-kit.htm#S4.2