Working with Files and Operating System in PHP

PHP provides built-in functions to interact with the file system, directories, and disk resources. These features are widely used in logs, uploads, backups, and system utilities.

File Functions in PHP

File functions allow PHP to create, read, write, update, and delete files.

Common File Functions

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Opening Files

fopen() Function

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

File Modes

Exam Tip: Always close a file after use.

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Reading Files

$file = fopen("test.txt", "r");
echo fread($file, filesize("test.txt"));
fclose($file);

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Creating & Writing Files

$file = fopen("data.txt", "w");
fwrite($file, "Welcome to PHP File Handling");
fclose($file);

Exam Line: If file does not exist, fopen() creates it in write mode.

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Deleting Files

unlink("data.txt");

Exam Point: unlink() permanently deletes a file.

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Creating Directories

mkdir() Function

mkdir("uploads");

Create Nested Directory

mkdir("files/images", 0777, true);

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Manipulating Directories

Example: List Files in Directory

$files = scandir("uploads");
print_r($files);

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Information about Hard Disk

PHP provides disk-related functions to get storage information.

Example

echo disk_total_space("C:");
echo disk_free_space("C:");

Exam Line: Disk functions return size in bytes.

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Directory Functions

Directory functions manage folders and file navigation.

Example

$dir = opendir("uploads");
while($file = readdir($dir)){
   echo $file;
}
closedir($dir);

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Calculating File, Directory and Disk Sizes

File Size

echo filesize("test.txt");

Directory Size (Logic Based)

$size = 0;
foreach(scandir("uploads") as $file){
   if(is_file("uploads/".$file)){
      $size += filesize("uploads/".$file);
   }
}
echo $size;

Disk Size

echo disk_total_space("/");

Exam Tip: Directory size is calculated by summing file sizes.