zed backup create to existing file #329

Hi,

I've reported this already in #284, but I found the solution and implementation there insufficient.

I'd love zed backup create to write to an existing file, maybe protected by a --force, for example a previously created /path/to/some/fifo where other processes can read the output from for further processing. Quoting the full description from the other issue:

I'd like to run backups using the provided docker images which don't have much other utilities, not even a shell to > redirect the stream on stdout AFAIK. I'm not keen to run my own images. The pattern I usually would use is that I send the data to a named pipe (created by mkfifo on a shared volume in an init container), have the zed container write to it and another container in the same pod read from it for further processing (compression, encryption, etc.). With zed refusing to write to the existing named pipe I cannot do that.

Let me know if you require any further information.

Kind regards,
Frank.