First of all, thanks for your replies and quick fixes Karel. Am 03.02.2011 13:17, schrieb Karel Zak: >> I would wish I could have a way to use blkid in a way, such that I will >> be able to determine (through its return value) whether a device >> contains any known file system, raid superblock, partition table, ... - >> anything I would not want to overwrite. > > > Note that "blkid -p" also returns "2" if ambivalent probing result > was detected (more superblocks on the device). In the next release > (v2.19) it will return "8" in this case. This was something I was a bit worried about, but ignored it - all recent versions of the commonly used tools (mkswap, cryptsetup, mkfs.*) avoid this situation entirely. It would only be a problem for legacy systems. > The best way to detect empty device is probably: > > if test -z "$(blkid -o udev -p $device -s TYPE -s PTTYPE)"; then > echo "nothing on the device" > fi > > this works in all cases and all util-linux blkid(8) versions. This will still return nothing in case of ambivalent results, right? Or would is print an ID_FS_AMBIVALENT line? However, with the changes queued up for 2.19, my method of using 'blkid -p' should do exactly what I want (correct me if I am wrong here). Raising the userspace requirement to 2.18 with the backported patches (they apply cleanly to the 2.18 source) or to 2.19 is not a problem in my case, so I'll probably go with that.
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