Where can I find error log files for PHP?

You can use lsof to find open logfiles on your system. lsof just gives you a list of all open files.

Use grep for "log" ... use grep again for "php" (if the filename contains the strings "log" and "php" like in "php_error_log" and you are the root user you will find the files without knowing the configuration).

lsof | grep log ... snip gmain 12148 12274 user 13r REG 252,1 32768 661814 /home/user/.local/share/gvfs-metadata/home-11ab0393.log gmain 12148 12274 user 21r REG 252,1 32768 662622 /home/user/.local/share/gvfs-metadata/root-56222fe2.log gvfs-udis 12246 user mem REG 252,1 55384 790567 /lib/x86_64-linux-gnu/libsystemd-login.so.0.7.1 ==> apache 12333 user mem REG 252,1 55384 790367 /var/log/http/php_error_log** ... snip 

lsof | grep log | grep php **apache 12333 user mem REG 252,1 55384 790367 /var/log/http/php_error_log** ... snip 

Also see this article on finding open logfiles: Find open logfiles on a Linux system

It works for me. How can we log all PHP errors to a log file?

Just add the following line to file /etc/php.ini to log errors to specified file – file /var/log/php-scripts.log

vi /etc/php.ini 

Modify the error_log directive:

error_log = /var/log/php-scripts.log 

Make sure display_errors is set to Off (no errors to end users):

display_errors = Off 

Save and close the file. Restart the web server:

/etc/init.d/httpd restart 

How do I log errors to syslog or Windows Server Event Log?

Modify error_log as follows:

error_log = syslog 

How can we see logs?

Login using ssh or download a log file /var/log/php-scripts.log using SFTP:

sudo tail -f /var/log/php-scripts.log 

This will definitely help you,

Enable PHP error logging

Or

In php.ini (vim /etc/php.ini or sudo vim /usr/local/etc/php/7.1/php.ini)

display_errors = Off log_errors = On error_log = /var/log/php-errors.log 

Make the log file, and writable by user www-data:

sudo touch /var/log/php-errors.log sudo chown $USER:www-data /var/log/php-errors.log 

It depends on what OS you are using and which web server.

On Linux and Apache, you can find the Apache error_log in folder /var/log/apache2/.

On CentOS with cPanel installed, my logs were in:

/usr/local/apache/logs/error_log 

To watch: tail -f /usr/local/apache/logs/error_log

This is a preferable answer in most use cases, because it allows you to decouple execution of the software from direct knowledge of the server platform, which keeps your code much more portable. If you are doing a lot of cron or CGI, this may not help directly, but it can be set into a configuration at web runtime that the cron and CGI scripts pull from to keep the log location consistent in that case.

You can get the current log file assigned natively to PHP on any platform at runtime by using:

ini_get('error_log'); 

This returns the value distributed directly to the PHP binary by the web server, which is what you want in 90% of use cases (with the glaring exception being CGI). CGI will often log to this same location as the HTTP web server client, but not always.

You will also want to check that it is writeable before committing anything to it to avoid errors. The configuration file that defines its location (typically either file apache.conf globally or vhosts.conf on a per-domain basis), but the configuration does not ensure that file permissions allow write access at runtime.

I am using CentOS 6.6 with Apache and for me error log files are in:

/usr/local/apache/log 

For Unix CLI users:

Most probably the error_log ini file entry isn't set. To verify:

php -i | grep error_log // error_log => no value => no value 

You can either set it in your php.ini CLI file, or just simply quickly pipe all standard error yourself to a file:

./myprog 2> myerror.log 

Then quickly:

tail -f myerror.log