As an experienced PHP programmer, know the following several PHP system-level functions, not enough! Get the System Information and debug the program should be able to use!
PHP System class functions
Assert function: Check if the assertion declaration is incorrect
extension_loaded function: Check if PHP extension is loaded
Get_cfg_var function: Gets the value of the PHP configuration option
Get_current_user function: Gets the name of the owner of the current PHP script
Get_defined_constants function: Returns an array containing the PHP predefined constant information
Get_extension_funcs function: Returns an array containing all the function names in the specified module
Get_include_path function: Returns information for the currently configured file containing path
Get_included_files function: Returns an array containing information about the file
Get_loaded_extensions function: Returns an array containing all the loading module information
GET_MAGIC_QUOTES_GPC function: Get status information for MAGIC_QUOTES_GPC
Get_magic_quotes_runtime function: Get state information of Magic_quotes_ Runtime
Get_required_files function: Returns an array containing information about the file
getenv function: Gets the value of the PHP environment variable
PHP System class functions
Getlastmod function: Gets the last modified time of the current PHP paging file
Getmygid function: Gets the GID number of the owner of the current PHP script page
Getmyinode function: Gets the inode number of the current PHP script page
Getmypid function: Get the PID of PHP
Getmyuid function: Gets the UID number of the owner of the PHP script page
getopt function: Get settings from the command line argument list
Getrusage function: Gets the current resource syntax
Ini_get_all function: Get all configuration options
Ini_get function: Gets the value of the configuration option
Memory_get_usage function: Returns the memory space occupied by the PHP script
Php_ini_scanned_files function: Returns a list of configuration files under the profile directory
Php_logo_guid function: Get the logo image guid
Php_sapi_name function: Get the interface type between PHP and Web server
Php_uname function: Gets the operating system information that the PHP script runs
Phpcredits function: Print credits list
phpinfo function: output PHP information
phpversion function: Get PHP version
Zend_logo_guid function: Get the GUID of Zend logo image
Zend_version function: Gets the version of the Zend engine
PHP Configuration class functions
assert_options function: Set or get a different declaration token
Ini_alter function: Set the value of PHP configuration options
Ini_restore function: Restore the value of the configuration option
Ini_set function: Set the value of PHP configuration options
putenv function: Setting environment variables
Restore_include_path function: Recovery file contains path configuration information
Set_include_path function: Set file include path configuration options
Set_magic_quotes_runtime function: Set magic_quotes run time
Set_time_limit function: Set maximum execution time
Other class functions
DL function: Load PHP Extension Module
Main function: Just a nominal main () function
Version_compare function: Compare PHP two version values
