4 ms·

So basically deleting the file as the last step before a shut down or reboot will work, is that correct?

mirimir 8y ago
I'll test that. Edit: OK, so I created a Debian VM, noted /etc/machine-id, deleted it, and rebooted. And found that it was still missing. Running systemd-machine-id-setup generated a new machine-id from the D-Bus machine ID. And it was the same as the initial one. But I also see in man machine-id: > The machine-id may also be set, for example when network booting, by setting the systemd.machine_id= kernel command line parameter or passing the option --machine-id= to systemd. A machine-id may not be set to all zeros.
- patrickg_zill 8y ago
  Does something like dd if=/dev/urandom bs=1 count=16 | hexdump Give you something that you can use?
  - mirimir 8y ago
    Well, the machine-id of that Debian VM was ... 38d05397c25548b4f4bda7751b5062 ... and ... $ FOO=`cat /dev/urandom | tr -dc a-z0-9 | head -c${1:-30}` $ echo $FOO 6we4gvnmx00w208ffty6i11m82rw6d But I have no clue whether systemd would be happy with that. Maybe later I can test more. Edit: Oops. Make that ... $ FOO=`cat /dev/urandom | tr -dc abcdef0-9 | head -c${1:-30}` $ echo $FOO b486935dbb9e9fe603328a19e2b5b4
    - deleted 8y ago
      [deleted]
    - justinclift 8y ago
      Maybe use pwgen? Something like: $ pwgen -1s 31 qHfKU46H2RA2WUr0EZ1zBHfIBLKZKuT
      - mirimir 8y ago
        I think that it needs to be hexadecimal. But not sure.
        justinclift 8y ago
        No worries. :)
JdeBP 8y ago
Incorrect. Machine IDs are stored in several places, some of which are not even files. * http://jdebp.uk./Softwares/nosh/guide/commands/machine-id.xml#STORAGE http://jdebp.uk./Softwares/nosh/guide/commands/machine-id.xm... They can be resurrected if not all storage locations are dealt with. Moreover, some systems use things like the SMBIOS product UUID. * http://jdebp.uk./Softwares/nosh/guide/commands/setup-machine-id.xml#FALLBACKS http://jdebp.uk./Softwares/nosh/guide/commands/setup-machine... The correct approach is not deleting files. * http://jdebp.uk./Softwares/nosh/guide/commands/erase-machine-id.xml http://jdebp.uk./Softwares/nosh/guide/commands/erase-machine... * https://lists.debian.org/debian-user/2019/03/msg00550.html https://lists.debian.org/debian-user/2019/03/msg00550.html
- mirimir 8y ago
  Thanks. So at boot, one would run "erase-machine-id". Then create a random 30-character hexadecimal number. And then either set "the systemd.machine_id= kernel command line parameter" to it. Or pass it via "the option --machine-id= to systemd".
  - JdeBP 8y ago
    No. % system-control cat machine-id start:#!/bin/nosh start:true stop:#!/bin/nosh stop:envdir env stop:erase-machine-id run:#!/bin/nosh run:#Set up and tear down the machine ID run:envdir env run:setup-machine-id restart:#!/bin/sh restart:exec false # ignore script arguments %
    - mirimir 8y ago
      OK, thanks. So "setup-machine-id". Does that generate a value that's unrelated to any preexisting versions, analogs, etc? I ask because, when I deleted /etc/machine-id and ran "systemd-machine-id-setup", it generated a new machine-id by copying the D-Bus machine ID.

I'll test that. Edit: OK, so I created a Debian VM, noted /etc/machine-id, deleted it, and rebooted. And found that it was still missing. Running systemd-machine-id-setup generated a new machine-id from the D-Bus machine ID. And it was the same as the initial one. But I also see in man machine-id: > The machine-id may also be set, for example when network booting, by setting the systemd.machine_id= kernel command line parameter or passing the option --machine-id= to systemd. A machine-id may not be set to all zeros.

patrickg_zill 8y ago
Does something like dd if=/dev/urandom bs=1 count=16 | hexdump Give you something that you can use?
- mirimir 8y ago
  Well, the machine-id of that Debian VM was ... 38d05397c25548b4f4bda7751b5062 ... and ... $ FOO=`cat /dev/urandom | tr -dc a-z0-9 | head -c${1:-30}` $ echo $FOO 6we4gvnmx00w208ffty6i11m82rw6d But I have no clue whether systemd would be happy with that. Maybe later I can test more. Edit: Oops. Make that ... $ FOO=`cat /dev/urandom | tr -dc abcdef0-9 | head -c${1:-30}` $ echo $FOO b486935dbb9e9fe603328a19e2b5b4
  - deleted 8y ago
    [deleted]
  - justinclift 8y ago
    Maybe use pwgen? Something like: $ pwgen -1s 31 qHfKU46H2RA2WUr0EZ1zBHfIBLKZKuT
    - mirimir 8y ago
      I think that it needs to be hexadecimal. But not sure.
      - justinclift 8y ago
        No worries. :)

JdeBP 8y ago

Incorrect. Machine IDs are stored in several places, some of which are not even files. * http://jdebp.uk./Softwares/nosh/guide/commands/machine-id.xml#STORAGE http://jdebp.uk./Softwares/nosh/guide/commands/machine-id.xm... They can be resurrected if not all storage locations are dealt with. Moreover, some systems use things like the SMBIOS product UUID. * http://jdebp.uk./Softwares/nosh/guide/commands/setup-machine-id.xml#FALLBACKS http://jdebp.uk./Softwares/nosh/guide/commands/setup-machine... The correct approach is not deleting files. * http://jdebp.uk./Softwares/nosh/guide/commands/erase-machine-id.xml http://jdebp.uk./Softwares/nosh/guide/commands/erase-machine... * https://lists.debian.org/debian-user/2019/03/msg00550.html https://lists.debian.org/debian-user/2019/03/msg00550.html

mirimir 8y ago
Thanks. So at boot, one would run "erase-machine-id". Then create a random 30-character hexadecimal number. And then either set "the systemd.machine_id= kernel command line parameter" to it. Or pass it via "the option --machine-id= to systemd".
- JdeBP 8y ago
  No. % system-control cat machine-id start:#!/bin/nosh start:true stop:#!/bin/nosh stop:envdir env stop:erase-machine-id run:#!/bin/nosh run:#Set up and tear down the machine ID run:envdir env run:setup-machine-id restart:#!/bin/sh restart:exec false # ignore script arguments %
  - mirimir 8y ago
    OK, thanks. So "setup-machine-id". Does that generate a value that's unrelated to any preexisting versions, analogs, etc? I ask because, when I deleted /etc/machine-id and ran "systemd-machine-id-setup", it generated a new machine-id by copying the D-Bus machine ID.