What to do if php exec cannot be executed

Solution to the problem that php exec cannot be executed: 1. Find the php configuration file php.ini, search for "disable_functions" in the file, and remove "exec" and "shell_exec"; 2. Go to the server to modify the file permissions ;3. Modify the safe mode in the configuration to "safe_mode=On".

The operating environment of this tutorial: Windows 7 system, PHP version 8.1, Dell G3 computer.

What should I do if php exec cannot be executed?

Analysis of the reasons why PHP exec fails to execute system instructions

Problem background:

Due to project requirements, it is necessary to Generate images from the html page, use the phantomjs (click to learn) tool to take screenshots of the page, and run it in the cmd window without any problems. But the exec operation failed in php, prompting that phantomjs is not an internal instruction.

Problem Solution:

Find various solutions in Baidu:

Option 1:

1. Modify php.ini

Find the php configuration file php.ini. If you use the php automatic installation program to configure the php environment, this file is in the C:\WINDOWS\ directory.

Search for "disable_functions" in the file, find it, remove "exec" and "shell_exec", and then save the file.

## 2. Modify the cmd.exe file properties

Enter C:\WINDOWS\system32, find the cmd.exe file, right-click->Properties, Add the Internet guest account in the "Security" settings, which is the IUSR_****** account, and then grant "Read and Run" and "Read" permissions.

Option 2:

Some say it is a permissions issue.

Solution:

https://www.php.cn/php-weizijiaocheng-498092.html

Option 3:

PHP's built-in functions exec and system can call system commands (shell commands), and of course there are functions such as passthru and escapeshellcmd.

In many cases, using PHP's exec, system and other functions to call system commands can help us complete our work better and faster. For example, exec helped me a lot when I was batch processing .rar files two days ago.

Today I will sort out the commonly used calling system functions and share my experience with everyone.

Note: If you want to use these two functions, the safe mode in php.ini must be turned off, otherwise PHP will not allow you to call system commands for security reasons.

Let’s first look at the explanation of these two functions in the PHP manual:

exec --- Execute external programs

语法 : string exec ( string command [, array &output [, int &return_var]] )

Description:

exec( ) Execute the given command command, but it does not output anything. It simply returns the last line from the result of the command. If you need to execute a command and get all the information from the command, you can use passthru() this function.

If the parameter array is given, the specified array will be filled with each line output by the command. Note: If the array already contains some elements, exec() will append it to the array. later, if you don't want this function to append elements, you can call unset() before passing the array to exec().

If the parameters array and return_var are given, the status command returned to execution will be written to this variable.

Note: If you allow data from user input to be passed to this function, then you should use escapeshellcmd() to ensure that the user cannot trick the system into executing arbitrary commands. .

Note: If you use this function to start a program and want to leave it while executing in the background, you must make sure that the output of the program is redirected to a file or some other Output data stream, otherwise PHP will hang until the program execution ends.

system --- Execute the external program and display the output

语法 : string system ( string command [, int &return_var] )

Description:

system() executes the given command command and outputs the result. If the parameter return_var is given, the status code of the executed command will be written to this variable.

Note: If you allow data from user input to be passed to this function, then you should use escapeshellcmd() to ensure that the user cannot trick the system into executing arbitrary commands. .

Note: If you use this function to start a program and want to leave it while executing in the background, you must make sure that the output of the program is redirected to a file or some other Output data stream, otherwise PHP will hang until the program execution ends.

If PHP is running as a server module, system() will try to automatically clear the web server's output buffer after outputting each line.

Returns the last line of the command if successful, false if failed.

If you need to execute a command and obtain all data from the command, you can use the passthru() function.

这二个都是用来调用系统shell命令，

不同点:

exec可以把执行的结果全部返回到$output函数里(数组),$status是执行的状态 0为成功 1为失败

systerm不需要提供$output函数，他是直接把结果返回出来，同样$return_var是执行的状态码 0为成功 1为失败

exec示例: 

以下为引用的内容：  

<?php  
$a = exec("dir",$out,$status);  
print_r($a);  
print_r($out);  
print_r($status);  
?>

system示例:

以下为引用的内容：  

<?php  
$a = system("dir",$out);  
print_r($a);  
print_r($out);  
?>

总结：

以上三个解决方案都是从百度搜索到的。

第一个解决方案我查看了配置，不存在这种情况，pass。

第二个解决方案由于需要改服务器权限，情况不允许，没试。

第三个解决方案参考了一下，修改了配置中的安全模式，safe_mode=On；然后问题迎刃而解。

OK，以上是我解决问题的过程。希望可以帮到广大像我一样的小白。

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