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Editor to share with you what is the use of the system function in php, I believe most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!

The system function in php is used to execute the external program and displays the output, using syntax such as "system (string $command, int & $return_var =?): string", which executes the command specified by the command parameter and outputs the execution result.

This article operating environment: Windows7 system, PHP7.1 version, Dell G3 computer.

System (PHP 4, PHP 5, PHP 7, PHP 8)

System-executes external programs and displays output

Description

System (string $command, int & $return_var =?): string

Like the C version of the system () function, this function executes the command specified by the command parameter and outputs the execution result.

If PHP is running in the server module, the system () function also attempts to automatically flush the output cache of the web server after each line has been output.

If you want to get the raw output of a command without any processing, use the passthru () function.

Parameters.

Command

The order to be carried out.

Return_var

If the return_var parameter is provided, the return state after the execution of the external command will be set to this variable.

Return value

Returns the last line of the command output for success and false for failure.

Sample system () routine

Annotation

When passing user-supplied data into this function, you should use escapeshellarg () or escapeshellcmd () to prevent the user from spoofing the system into executing arbitrary commands.

Note:

How to start a program using this function? in order to keep running in the background, the program must redirect the output to a file or other output stream. Otherwise, it will cause PHP to hang until the end of program execution.

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