php system variable settings

With the popularity of PHP language, more and more people are beginning to use PHP programming to develop websites. When writing PHP code, you need to set some system variables to adapt to different situations. This article will discuss the setting of PHP system variables.

1. What are system variables

System variables refer to variables defined in PHP files. These variables are generated during the running of PHP. The purpose of system variables is to help programmers debug and set them at runtime.

2. How to set system variables

In PHP, system variables can be set in two ways: through ini files or through PHP functions.

1. Setting through ini file

PHP provides a configuration file named php.ini, which is used to set the configuration parameters of PHP runtime. By modifying this file, you can set some system variables of PHP.

Suppose you want to set the PHP running time limit to 60 seconds, you can find the following line in the php.ini file:

; Maximum execution time of each script, in seconds
; http ://php.net/max-execution-time
; Note: This directive is hardcoded to 0 for the CLI SAPI
max_execution_time = 30

Set the value of the "max_execution_time" line to 60 , you can set the PHP running time limit to 60 seconds. Of course, there are many other configuration parameters that can be set in php.ini.

It should be noted that before setting system variables by modifying the php.ini file, you need to ensure that you have access to the file. Otherwise, you will receive permission errors.

2. Setting through PHP function

In addition to setting system variables through ini files, you can also use PHP's built-in ini_set() function or putenv() function to set system variables. These functions can be used anywhere in your PHP code, allowing you to flexibly adjust your program's settings.

For example, to set the PHP running time limit to 60 seconds, you can use the following statement in the code:

ini_set("max_execution_time", "60");

Or set it through the putenv() function:

putenv("max_execution_time=60");

The "max_execution_time" in the above statement is the name of the system variable, and "60" is for the value set. Setting it in code also allows for more flexible adjustments.

3. Commonly used system variables

The following are some commonly used system variables:

1. max_execution_time: Specify the maximum running time of the PHP script, in seconds.

2. memory_limit: Specify the maximum amount of memory that the PHP script can use.

3. error_reporting: Specify the level of PHP error reporting.

4. display_errors: If the value is true, PHP will display error information in the browser.

5. date.timezone: Specify the time zone used by PHP. It can be set in the php.ini file or through the date_default_timezone_set() function.

6. max_input_time: Specify the maximum time from the request to receiving POST/GET data.

4. Summary

System variables are a method widely used in the PHP language, which can help developers debug and optimize code. This article introduces how to set system variables through the php.ini file and PHP functions, and lists some commonly used system variables and their functions. Hope this article is helpful to PHP developers.

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