Y'd think that 'dd' would do what it is told and read the correct block
size rather than returning a 'short'. Would one consider this a
possible "undesired feature" [bug] in 'dd', if that proves to be the
problem? Seems like there should at least be a way to say for it to wait
for short blocks. Hmph.
oh well.
thanks for all the pointers.
Linda
Pete Zaitcev wrote:
>
> > dd if=/dev/hda2 bs=1M|rsh other-system of=/dev/sda2 bs=1M
>
> That does not work on all unixes. Perhaps it does on IRIX,
> but certainly not on Solaris. The remote dd is going to
> get short reads from the socket. The telltale sign is the
> number to short records:
>
> itcev@niphredil /boot]$ dd if=vmlinux-2.4.7-niph bs=8k | ssh pentabug dd of=xxx bs=8k
> 333+1 records in
> 333+1 records out
> 7+653 records in <------- almost all are shorts
> 7+653 records out
> [zaitcev@niphredil /boot]$
>
> There is no good way to deal with it, unless you use some external
> filter (perhaps netcat?). tar has a flag -B to deal with this.
> An oldtimer's trick is to use compress, which works because
> zcat uses stdio for output and its blocksize is fixed.
>
> [zaitcev@niphredil /boot]$ dd if=vmlinux-2.4.7-niph bs=8k | compress | ssh pentabug "zcat |dd of=xxx bs=8k"
> 333+1 records in
> 333+1 records out
> 333+1 records in
> 333+1 records out
> [zaitcev@niphredil /boot]$
>
> This behaviour of sockets on Linux is entirely normal, so deal with it.
> My pet peeve is how DaveM insists that WRITES to a socket may return
> short. That stupidity just makes me furious each time. A socket has
> a posix-schmozix "right" to return short, I agree. But it is extremely
> rude and in the right implementation, it should not. It breaks just
> about _every_ application that uses printk.
>
> -- Pete
-- - _ - _ - _ - _ - _ - _ - _ -
L A Walsh, law at sgi dot com | Senior Engineer
01-650-933-5338 | Trust Technology, Core Linux, SGI
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