The difference between shell_exec() and exec() functions in php

Recommended manual: php complete self-study manual

shell_exec() function is a built-in function in PHP that is used to execute commands through the shell and return the complete output as a string. shell_exec is an alias for the backtick operator, used in *nix. NULL is returned if the command fails, and these values ​​are not reliable for error checking.

Syntax:

string shell_exec( $cmd )

Parameters: This function accepts a single parameter $cmd, which is used to save the command to be executed.

Return value: This function returns the executed command, or NULL if an error occurs.

Note: This feature is disabled when PHP is running in safe mode.

Example:

<?php 
  
// 使用ls命令来执行shell_exec函数
$output = shell_exec(&#39;ls&#39;); 
  
// 显示所有文件和目录的列表
echo "<pre class="brush:php;toolbar:false">$output

"; ?>

Output:

gfg.php 
index.html 
demo.php

exec() function is a built-in function in PHP, used to execute external programs and return output the last line. It also returns NULL if the command was not run correctly.

Syntax:

string exec( $command, $output, $return_var )

Parameters: This function accepts the above three parameters, as described below:

$command: This parameter is used to save the command to be executed.

$output: This parameter is used to specify the array that will be populated with each line of output from the command.

$ return_var: The $return_var parameter comes along with the output parameters, then it returns the status of the executed command will be written to this variable.

Return value: This function returns the executed command. Please be sure to set and use the output parameters.

Example:

<?php 

echo exec(&#39;iamexecfunction&#39;); 
?>

Output:

demo.php

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