In this post you will find how to configure PHP to log errors and warnings to the separate log file - error_php. You can place error_php wherever you want, but I will suggest to choose the /tmp directory. Why not /var/log/httpd directory where Apache keeps log files? Because anyone who can write to the directory where Apache is writing a log file can almost certainly gain access to the uid that the server is started as, which is normally root. More about logs and security can be read on Apache: Log Files
1. Set error log path in /etc/php.ini
Open /etc/php.ini file, find line with error_log and set absolute path to the error_php file. Lines started with ";" are comments, so be sure to remove ";" if there is any.
# php.ini error_log = /tmp/error_php
Next find log_errors line in php.ini file. Default value is "On" so logging already should be enabled. If not, please write "On".
# php.ini log_errors = On
2. Restart Apache
Now you have to restart Apache server, and error_php file should appear in /tmp directory.
# tip 1: restart Apache bash> /etc/init.d/httpd restart # tip 2: restart Apache bash> service httpd restart
As you can see, in two steps PHP errors and warnings can be redirected to the separate file.