Re: emulate an end-of-media

Mike Meyer wrote:

On Mon, 25 Feb 2008 21:19:33 +0100 "Martin Laabs" <martin.laabs@xxxxxxxxxxxxxxxxxxxxx> wrote:


Hi,

On Mon, 25 Feb 2008 20:34:31 +0100, wrote:



You might want to play with the -P option to dump. Your above could be
written as:

dump -aL0 -P 'compress -c' /MYFILESYSTEM | cdrecord dev=... -



Why compress? It's ancient technology and will be vastly outperformed by gzip (and bzip2 but that's slower).

Assuming that compress -c & cdrecord play nice (which your magic
device solution also requires)


My solution can just close the pipe at the one "end" of the magic
device which would be realy simple to implement in a script.



While you're proposing a magic device that catches sigpipe, and
delivers an EOM to make dump -a happy. I'm proposing that dump catch
the sigpipe, and treat it like an EOM if it has -a. This may be
non-workable, in that you have to be able to tell if it was the -P
process or a slave process that generated the sigpipe, but I think
it's the best solution.


Are there not (at least) two more alternatives?

1) Add gzip/zlib support to dump. That would seem easier than new devices. Then -a would just work.

2) Instead of using cdrecord directly you have a wrapper which "emulates" the dump -a behaviour by writing 650/700Mb of data using cdrecord then prompting for the next cd. You don't close the pipe, and dump should just block waiting for your "device" to be ready. Might have trouble accessing /dev/tty - not sure.

--Alex

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