Linux system functions for PHP functions

PHP is a widely used server-side programming language. It has a wide range of applications and has very powerful functions in network programming, database operations, file processing, etc. PHP has many built-in functions that can be called directly to complete various tasks. Among them, functions related to Linux systems play a very important role. In this article, we will detail the Linux system functions of PHP functions.

1. File-related functions

1. fopen() function: This function is used to open a file in the specified mode and return a file handle. Commonly used modes are "r" (read only), "w" (write only), and "a" (append), among which "r", "w", and "a" perform read and write operations on files. For example:

$file = fopen("file.txt","r");

2. fclose() function: This function is used to close an open file , release the file handle. For example:

fclose($file);

3. fwrite() function: This function is used to write content to a file. For example:

fwrite($file,"Hello World!");

4. file_exists() function: This function is used to check whether the file exists. For example:

if(file_exists("file.txt")){

echo "文件存在";

}else{

echo "文件不存在";

}

5. file_get_contents() function: This function is used to read the file contents into a string. For example:

$content = file_get_contents("file.txt");

2. Process-related functions

1. exec() function: This function Used to execute a shell command. For example:

exec("ls -al");

2. system() function: This function is also used to execute a shell command and output the results. For example:

system("ls -al");

3. passthru() function: This function is used to execute a shell command and output the result directly. For example:

passthru("ls -al");

4. proc_open() function: This function is used to start a new process and establish a connection with it. For example:

$descriptorspec = array(
0 => array("pipe", "r"), // Standard input
1 => array("pipe" , "w"), // Standard output
2 => array("file", "/tmp/error-output.txt", "a") // Standard error output
);
$process = proc_open('php script.php', $descriptorspec, $pipes);

5. proc_close() function: This function is used to close a process. For example:

proc_close($process);

3. Network related functions

1. fsockopen() function: This function is used to open a network socket connect. For example:

$fp = fsockopen("www.example.com", 80);

2. fwrite() function: This function is used to write to the network socket data. For example:

fwrite($fp, "GET / HTTP/1.0
Host: www.example.com

");

3. fgets() function: This function is used to read data from the network socket. For example:

while(!feof($fp)) {
echo fgets($fp, 1024);
}

4. fclose() function : This function is used to close a network socket connection. For example:

fclose($fp);

4. Other functions

1. shell_exec() function: This function is used to execute a shell command. and returns the result as a string. For example:

$output = shell_exec('ls -al');

2. system_status() function: This function is used to obtain system status information. For example:

$status = system_status();

3. posix_getuid() function: This function is used to obtain the user ID of the current process. For example:

$uid = posix_getuid();

Conclusion:

Linux operating system is a very important server operating system. PHP, as a server-side programming language, is closely related to Linux. This article introduces the Linux system functions of PHP functions, which are mainly divided into file-related functions, process-related functions, network-related functions and other functions. These functions are very useful and help us easily access various features of the Linux operating system in PHP programs and improve the development efficiency and functionality of the program.

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