how to tell where it booted from

[Mike Wright]

On 02/15/2016 04:21 PM, Rick Stevens wrote:
> On 02/15/2016 03:42 PM, Mike Wright wrote:
>> Does the boot process leave any footprints behind telling where it
>> booted from?
>>
>
> You can always "cat /proc/cmdline" to see what the boot command line
> was. In my case:
>
>      [root at prophead ~]# cat /proc/cmdline
>      BOOT_IMAGE=/vmlinuz-4.3.4-200.fc22.x86_64
> root=/dev/mapper/fedora-root ro rd.lvm.lv=fedora/swap
> vconsole.font=latarcyrheb-sun16 rd.lvm.lv=fedora/root rhgb quiet
> LANG=en_US.UTF-8
>
> So it booted the 4.3.4-200.fc22.x86_64 kernel (yes, this machine is
> still F22) and the current /dev/mapper/fedora-root is the root of my
> filesystem. Digging a bit more:
>
>      [root at prophead ~]# ls -l /dev/mapper/fedora-root
>      lrwxrwxrwx. 1 root root 7 Feb  1 15:09 /dev/mapper/fedora-root
> -> ../dm-1
>      [root at prophead ~]# ls -l /dev/dm-1
>      brw-rw----. 1 root disk 253, 1 Feb  1 15:09 /dev/dm-1
>
> So, /dev/mapper/fedora-root is is /dev/dm-1 or device major 253, minor
> 1. Dig a bit deeper:
>
>      [root at prophead ~]# lsblk
>      NAME            MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
>      sda               8:0    0 931.5G  0 disk
>      ├─sda1            8:1    0   500M  0 part /boot
>      └─sda2            8:2    0   931G  0 part
>        ├─fedora-swap 253:0    0  15.6G  0 lvm  [SWAP]
>        ├─fedora-root 253:1    0 606.8G  0 lvm  /
>        ├─fedora-home 253:2    0   293G  0 lvm  /home
>        └─fedora-tmp  253:3    0  15.6G  0 lvm  /tmp
>      sdb               8:16   0 465.8G  0 disk
>      └─sdb1            8:17   0 465.8G  0 part /media/500GB-Drive
>      sr0              11:0    1     2K  0 rom
>
> So you can see my boot partition is a plain-old partition on /dev/sda1
> and the root filesystem (block device 253:1) is a Linux LVM living on
> /dev/sda2.
>
> Does that help any?

Hi Rick,

Thanks but not the cigar I was looking for.  "lsblk" has 49 entries, 
none of which are boot which would seem to indicate /boot in question is 
on the mapped root.  But changes made to that grub.cfg don't show up in 
the options available in the subsequent boot.  Since that does seem to 
be the smoking gun I'll check it again.