Hello S., sorry for the really late reply! Just cleaning up my mailbox, and that was forgotten. S. Sara [2019-10-21 15:52 +0000]: https://github.com/cockpit-project/cockpit/issues/12338 has some details about this. Indeed this needs documentation and some refinement (Stef recently made the chunking better), but at least with spawning a process like dd, having that write the output file, and feeding blocks into it with .input() seems like a workable solution for now. It of course would be better if the cockpit.file() API would support sending the contents in multiple chunks, but cockpit.js doesn't currently do that. However, the *protocol* [1] does allow it. I. e. you can open a raw channel [2] with the payload="fsreplace1" type, and feed the data using channel.send() in multiple blocks. I'm not aware of an existing example there, but that's IMHO the most elegant and efficient way. Thanks, Martin [1] https://github.com/cockpit-project/cockpit/blob/master/doc/protocol.md#pa... [2] https://cockpit-project.org/guide/latest/cockpit-channels.html