How does PHP use command line tools and system calls?

PHP is a programming language widely used in web development, but it is not limited to web applications. PHP also provides powerful command line tools and system call functions, allowing developers to use PHP to perform various system-level tasks. This article will introduce how PHP uses command line tools and system calls.

1. Command line tool

1. Execute PHP script through command line
   Enter the following command on the command line to execute PHP script:

   php script.php

   This method allows you to execute PHP scripts directly on the command line and pass command line parameters to the script.

2. Command line parameters
   PHP scripts can receive command line parameters. In the script, you can use the $argc variable to get the number of parameters, and the $argv array to get the specific parameter values. The following is a simple example:

   <?php
   // script.php
   for($i = 0; $i < $argc; $i++) {
    echo "参数".$i.":".$argv[$i]."
   ";
   }
   ?>

   Execute the following command in the command line:

   php script.php foo bar

   will output the following results:

   参数0:script.php
   参数1:foo
   参数2:bar

3. Get the command Line output
   Sometimes, we want to get the output of command line execution in a PHP script. You can use the exec() or shell_exec() function to execute a command and obtain its output. The following is a simple example:

   <?php
   $output = exec("ls -l");
   echo "命令行输出:".$output."
   ";
   ?>

   This code executes the ls -l command and stores the output in the $output variable, and finally outputs it .

2. System call
In addition to executing command line tools, PHP also provides system call functions with more powerful functions, which can achieve more complex system-level tasks.

1. Execute system commands
   system()The function can be used to execute system commands and print its output to standard output. The following is a simple example:

   <?php
   $cmd = "ls -l";
   system($cmd);
   ?>

   This code executes the ls -l command and prints the results to standard output.

2. Execute an external program
   exec()The function allows the execution of an external program and returns its output. The following is a simple example:

   <?php
   $cmd = "php -v";
   $output = exec($cmd);
   echo "输出:".$output."
   ";
   ?>

   This code executes the php -v command and stores the output in the $output variable and finally outputs it .

3. Execute system calls
   system() and exec() functions can only execute a command or program once and cannot capture its output . If you need to execute multiple commands or programs and capture their output, you can use the proc_open() function. The following is a simple example:

   <?php
   $descriptorspec = array(
    0 => array("pipe", "r"),
    1 => array("pipe", "w"),
    2 => array("file", "/tmp/error-output.txt", "a")
   );
   
   $process = proc_open('ls -l', $descriptorspec, $pipes);
   
   if (is_resource($process)) {
     while ($line = fgets($pipes[1])) {
        echo $line;
    }
   
    fclose($pipes[0]);
    fclose($pipes[1]);
   
    $return_value = proc_close($process);
   
    echo "返回值:".$return_value."
   ";
   }
   ?>

   This code executes the ls -l command and prints the output to standard output.

Summary:
PHP provides a wealth of command line tools and system call functions that can help developers perform various system-level tasks. Whether it is executing a command line tool or making a system call, PHP provides corresponding functions to implement it. Developers can choose appropriate functions to complete tasks according to their own needs. I hope this article will help you understand how PHP uses command line tools and system calls.

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