public abstract FileOutputStream append_to (FileCreateFlags flags, Cancellable? cancellable = null) throws Error

Gets an output stream for appending data to the file.

If the file doesn't already exist it is created.

By default files created are generally readable by everyone, but if you pass PRIVATE in flags the file will be made readable only to the current user, to the level that is supported on the target filesystem.

If cancellable is not null, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error g_io_error_cancelled will be returned.

Some file systems don't allow all file names, and may return an g_io_error_invalid_filename error. If the file is a directory the g_io_error_is_directory error will be returned. Other errors are possible too, and depend on what kind of filesystem the file is on.

Example: Append to file, sync:

public static int main (string[] args) {
// Open or create a file for appending:
File file = File.new_for_path ("my-test.txt");
try {
// Append a new line on each run:
FileOutputStream os = file.append_to (FileCreateFlags.NONE);
os.write ("My new line\n".data);
} catch (Error e) {
print ("Error: %s\n", e.message);

return 0;

valac --pkg gio-2.0 GLib.File.append_to.vala



input File


a set of FileCreateFlags


optional Cancellable object, null to ignore


a FileOutputStream, or null on error. Free the returned object with unref.