The following are examples of php_syscalls.d. This is a simple script to count executed PHP functions and system calls. Here it traces an example program, Code/Php/func_abc.php # php_syscalls.d Tracing... Hit Ctrl-C to end. ^C PID FILE TYPE NAME COUNT 18419 func_abc.php func func_a 1 18419 func_abc.php func func_b 1 18419 func_abc.php func func_c 1 18419 func_abc.php func sleep 3 18419 httpd syscall nanosleep 3 While tracing, four functions were called - func_a(), func_b(), func_c(), and sleep. There were also three instances of the system call nanosleep(). This script can provide an insight to how a PHP application is interacting with the system, by providing both application function calls and system calls in the same output.