Linda Walsh wrote: > Sometimes I would like "dd" to copy the contents of > "Random-Block-Object-A" > to "Random-Block-Object-B", starting from the middle of of the file. > > I can specify the "seek=BLOCKS" param, but it appears that "dd" doesn't > translate this to a "seek" command but instead uses "read" to to > sequentially access the block device. Is this the case or am I > hallucinating?
I think you are hallucinating. Put an strace before your dd command to confirm. seek is a pretty fundamental feature of a block device :) > > If I am not hallucinating, I can see this being done by design > from a historical perspective, working with tapes or such, but I'm > not sure it makes as much sense today. Perhaps an attempt at an lseek > on an "OS", and if that fails, then failover to the older "read" > behavior? > > If it is deemed necessary, maybe some flag to force old behavior? > > It gets painful when copying multi-gigabyte images where one may have > already copied previous parts of an image. > > Second question I had -- at times, it seems like various utils > are limited to 2G file offsets on OS's (i686-linux, i686-cygwin) > that support files >2G. Is this "old" behavior that will (should?) > be disappearing? I'd noticed it before in specifying counts > and such in "dd" (among others). What platform, filesystem and version of dd are you using? I've confirmed on my fedora core 3 & ubuntu 5.10 systems that I can seek to 2TB with the command `truncate 2TB ext3.test`: http://www.pixelbeat.org/scripts/truncate Pádraig. _______________________________________________ Bug-coreutils mailing list [email protected] http://lists.gnu.org/mailman/listinfo/bug-coreutils
