(PHP ActiveX) Compress a File to Gzip with Custom Metadata

See more Gzip Examples

This example demonstrates how to use the CompressFile method to create a Gzip (.gz) file while customizing the metadata embedded in the Gzip header.

Before compression, several properties are set:

• Comment: Adds a descriptive comment to the Gzip file.
• Filename: Specifies the filename to embed in the Gzip data, which may be used by extraction tools as the default output name.
• CompressionLevel: Controls the tradeoff between compression ratio and speed (set to maximum in this example).
• LastModStr: Sets the last-modified timestamp using an RFC 822 formatted date string.

After setting these properties, the input file is compressed and written to a .gz file. This approach allows you to embed meaningful metadata along with the compressed data.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows Note: The php_com_dotnet.dll may need to be enabled inside of php.ini.

<?php

$success = 0;

// This example demonstrates how to compress a file to Gzip format
// while setting custom metadata such as comment, filename,
// compression level, and last-modified date.

$gzip = new COM("Chilkat.Gzip");

// Set custom Gzip properties:
$gzip->Comment = 'Example Gzip file created with Chilkat';
$gzip->Filename = 'custom_name.txt';
$gzip->CompressionLevel = 9;
$gzip->LastModStr = 'Wed, 1 Apr 2025 12:45:26 -0500';

// The file to be compressed:
$inputFile = 'example.txt';
$outputFile = 'example.txt.gz';

// Compress the file:
$success = $gzip->CompressFile($inputFile,$outputFile);
if ($success == 0) {
    print $gzip->LastErrorText . "\n";
    exit;
}

print 'Compression successful.' . "\n";
print 'Gzip file created: ' . $outputFile . "\n";

?>