On 23/02/14 21:00, Reco wrote: > Hi. > > On Sun, 23 Feb 2014 11:45:26 +1100 > David <bouncingc...@gmail.com> wrote: > >> whereas if you know that you do actually want the output file, it will >> be quicker to >> read it once and then checksum the file like this: >> # dd if=/dev/cdrom bs=2048 count=23150592 conv=notrunc,noerror > cd.iso >> # md5sum cd.iso > > You can read the device once, write the result to the file AND calculate the > checksum at the same time: > > dd if=/dev/cdrom bs=2048 count=23150592 conv=notrunc,noerror | tee cd.iso | > md5sum
1++ You 'could' then compare that md5sum to the one on the cdimage site - if it's a stock CD. If it's not, and I don't misunderstand the "noerror" parameter for dd, then it 'might' be a good idea to compare the md5sum of the CD *before* copying it. e.g.:- $ md5sum /dev/sr0;dd if=/dev/cdrom bs=2048 count=23150592 conv=notrunc,noerror | tee cd.iso | md5sum The comparison of md5sums, either of the original CD and the copy, or the cdimage site md5sum and the copy could easily be automated. NOTE: the documentation suggests the cd copy command is run as root - that's un-necessary, and like the running of any command as root that doesn't actually need to be run as root - unwise. > > Reco > > Kind regards -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/5309ca27.6000...@gmail.com
