Hi Antonio, > > It occurred to me that ddrescue(1) would do a better job, but I > > wouldn't want a copy created in an output file. I skimmed > > https://www.gnu.org/software/ddrescue/manual/ddrescue_manual.html > > but didn't see a way to do this, or a special meaning to an output > > file of /dev/null. > > Thanks. I'll document this. As you suggest, /dev/null (combined with a > mapfile) can be used to perform this task efficiently with a command > like this one: > > ddrescue -f -r-1 /dev/sdcard /dev/null mapfile
Thanks. I should have also asked: is using /dev/null a special value that avoids the write(2) system calls, e.g. as shown by ‘strace -c’? -- Cheers, Ralph.