Filesystem · Function

appendfile

Appends data to the end of a file, creating it if absent.

function appendfile(path: string, data: string): ()

Synopsis

How it works

Appends data to the end of an existing file without overwriting its contents. Uses CreateFileA with OPEN_ALWAYS disposition and seeks to end:

CreateFileA(path, FILE_APPEND_DATA, FILE_SHARE_READ,
            NULL, OPEN_ALWAYS, 0, NULL);
// OPEN_ALWAYS: open if exists, create if not
SetFilePointer(handle, 0, NULL, FILE_END);
WriteFile(handle, data, dataLen, &bytesWritten, NULL);
CloseHandle(handle);

Creates the file if it doesn’t exist. The FILE_APPEND_DATA access right ensures the write always goes to the end, even if another process is writing concurrently. Ideal for log files.

Usage

Append to a log

appendfile("log.txt", os.date() .. " ">-- joined game\n")

Parameters

path string

Path to the file.

data string

The content to append.