Arch Linux

itguy92075

Member

Registered: 2018-03-04

Posts: 9

archiso and UUIDs

Hello Arch Experts,

I'm using archiso to create live ISO images (works great BTW).  I have a couple of questions regarding ISOs' UUIDs.  For example:

# blkid /dev/sr0
/dev/sr0: UUID="2018-03-04-16-27-05-00" LABEL="archlinux" TYPE="iso9660" PTUUID="092f7849" PTTYPE="dos"

1) Where is UUID set?
2) Can I change it?

The build script has lots of useful options, but UUID is not among them.

TIA for any/all pointers and advice.

progandy

Member

Registered: 2012-05-17

Posts: 5,280

Re: archiso and UUIDs

iso9660 doesn't have a real UUID. Linux and GRUB treat the creation timestamp (including centiseconds) as the UUID.
archiso relies on xorriso which has the option

-volume_date "uuid" $YYYYMMDDhhmmsscc 

-volume_date type timestring
...
              when the ISO is produced. They can be influenced by "uuid".
              "uuid"  sets a timestring that overrides "c" and "m" times
              literally and sets the time of the El Torito boot catalog.  It
              must consist of 16 decimal digits which form YYYYMMDDhhmmsscc,
              with YYYY between 1970 and 2999. Time zone is GMT.  It is supposed
              to match this GRUB line:
               search --fs-uuid --set YYYY-MM-DD-hh-mm-ss-cc

...

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| alias CUTF='LANG=en_XX.UTF-8@POSIX ' |

itguy92075

Member

Registered: 2018-03-04

Posts: 9

Re: archiso and UUIDs

That explains why there's no UUID option.  Your solution will work for me.  Thanks!