an optional entity tag for the current #GFile, or #NULL to ignore
true if a backup should be created
a set of #GFileCreateFlags
optional #GCancellable object, null to ignore
a #GFileOutputStream or null on error. Free the returned object with gobject.object.ObjectG.unref.
Returns an output stream for overwriting the file, possibly creating a backup copy of the file first. If the file doesn't exist, it will be created.
This will try to replace the file in the safest way possible so that any errors during the writing will not affect an already existing copy of the file. For instance, for local files it may write to a temporary file and then atomically rename over the destination when the stream is closed.
By default files created are generally readable by everyone, but if you pass gio.types.FileCreateFlags.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 gio.types.IOErrorEnum.Cancelled will be returned.
If you pass in a non-null etag value and file already exists, then this value is compared to the current entity tag of the file, and if they differ an gio.types.IOErrorEnum.WrongEtag error is returned. This generally means that the file has been changed since you last read it. You can get the new etag from gio.file_output_stream.FileOutputStream.getEtag after you've finished writing and closed the #GFileOutputStream. When you load a new file you can use gio.file_input_stream.FileInputStream.queryInfo to get the etag of the file.
If make_backup is true, this function will attempt to make a backup of the current file before overwriting it. If this fails a gio.types.IOErrorEnum.CantCreateBackup error will be returned. If you want to replace anyway, try again with make_backup set to false.
If the file is a directory the gio.types.IOErrorEnum.IsDirectory error will be returned, and if the file is some other form of non-regular file then a gio.types.IOErrorEnum.NotRegularFile error will be returned. Some file systems don't allow all file names, and may return an gio.types.IOErrorEnum.InvalidFilename error, and if the name is to long gio.types.IOErrorEnum.FilenameTooLong will be returned. Other errors are possible too, and depend on what kind of filesystem the file is on.