PHP Delete Function
last modified April 3, 2025
The PHP unlink function is used to delete files from the filesystem.
It's the primary way to remove files programmatically in PHP applications.
Basic Definition
The unlink function deletes a file from the filesystem. It takes
one mandatory parameter (filename) and returns true on success or false on failure.
Syntax: unlink(string $filename, ?resource $context = null): bool.
The function requires proper permissions to delete the specified file.
Basic File Deletion Example
This shows the simplest usage of unlink to delete a file.
<?php
declare(strict_types=1);
$file = "test.txt";
if (file_exists($file)) {
if (unlink($file)) {
echo "File deleted successfully.";
} else {
echo "Error deleting file.";
}
} else {
echo "File does not exist.";
}
This checks if the file exists before attempting deletion. The unlink
function returns true if successful. Always check file existence first.
Deletion with Error Handling
Proper error handling makes file deletion more robust in production.
<?php
declare(strict_types=1);
function deleteFile(string $filename): bool {
if (!file_exists($filename)) {
throw new RuntimeException("File not found: $filename");
}
if (!is_writable($filename)) {
throw new RuntimeException("No write permission: $filename");
}
return unlink($filename);
}
try {
deleteFile("data.csv");
echo "File deleted successfully.";
} catch (RuntimeException $e) {
echo "Error: " . $e->getMessage();
}
This example demonstrates comprehensive error handling. It checks file existence and write permissions before attempting deletion. Exceptions provide clear errors.
Deleting Multiple Files
You can delete multiple files by iterating through an array of filenames.
<?php
declare(strict_types=1);
$files = ["temp1.txt", "temp2.txt", "temp3.txt"];
foreach ($files as $file) {
if (file_exists($file)) {
if (unlink($file)) {
echo "Deleted: $file\n";
} else {
echo "Failed to delete: $file\n";
}
} else {
echo "Not found: $file\n";
}
}
This loops through an array of files and attempts to delete each one. Each operation is handled individually with its own success/failure message.
Secure File Deletion
For sensitive data, consider secure deletion methods that overwrite files.
<?php
declare(strict_types=1);
function secureDelete(string $filename, int $passes = 3): bool {
if (!file_exists($filename)) return false;
$filesize = filesize($filename);
$handle = fopen($filename, 'r+');
for ($i = 0; $i < $passes; $i++) {
ftruncate($handle, 0);
fwrite($handle, str_repeat("\0", $filesize));
fflush($handle);
}
fclose($handle);
return unlink($filename);
}
secureDelete("sensitive_data.db");
This function overwrites the file with null bytes before deletion. While not perfect, it provides better security than simple deletion for sensitive data.
Deleting Files with Wildcards
PHP can delete multiple files matching a pattern using glob.
<?php
declare(strict_types=1);
$pattern = "logs/*.tmp";
foreach (glob($pattern) as $file) {
if (is_file($file)) {
unlink($file);
echo "Deleted: $file\n";
}
}
This example finds all .tmp files in the logs directory and deletes them.
The glob function expands the wildcard pattern into filenames.
Best Practices
- Check Permissions: Verify write access before deletion.
- Error Handling: Implement proper error handling.
- Backup: Consider backups before mass deletions.
- Security: Validate file paths to prevent directory traversal.
- Logging: Log deletion operations for audit purposes.
Source
This tutorial covered the PHP file deletion function with practical examples showing different usage scenarios and best practices.