Lua

Set a Custom Last-Modified Date in a Gzip File

See more Gzip Examples

This example demonstrates how to use the SetDt method to specify a custom last-modified date and time that will be embedded in a Gzip file.

A CkDateTime object is first initialized with a specific date/time using an RFC 822 formatted string. This date/time is then applied to the Gzip object using SetDt.

When a compression method is called (such as CompressStringToFile), the specified date/time is included in the Gzip metadata. This allows the resulting .gz file to carry a meaningful timestamp rather than using the current system time.

Lua

local chilkat = require("chilkat")

-- This example demonstrates how to set a custom last-modified date/time
-- that will be embedded in a Gzip file.

local gzip = chilkat.Gzip.new()
local dt = chilkat.DateTime.new()

-- Set the date/time using a timestamp format (ISO 8601 style):
dt:set_from_timestamp("2025-11-15T12:45:26-05:00")

-- Apply the date/time to the Gzip object:
local success = gzip:set_dt(dt)
if not success then
    print(gzip.last_error_text)
    return
end

-- Compress a string so the custom date/time is embedded in the .gz:
local inputStr = "Example text for Gzip compression."
success = gzip:compress_string_to_file(inputStr, "utf-8", "output.gz")
if not success then
    print(gzip.last_error_text)
    return
end

print("Gzip file created with custom last-modified date.")