How to chroot in Sabayon Linux

May 2, 2019 Leave a comment

Example 1: Sabayon Linux was installed in conventional partitions

Let’s say, for example, that the installation has three partitions: /dev/sda1 (EFI System Partition formatted with FAT32); /dev/sda2 (root partition formatted with ext4); /dev/sda3 (linuxswap). Modify the mount command below accordingly if the root directory is on a different partition. In this example, /boot is on the same partition as root (/) and therefore does not need to be mounted separately.

Boot a Sabayon Linux LiveDVD or LivePenDrive, open a terminal window and enter the following commands:

sabayonuser@sabayon ~ $ su
sabayon sabayonuser # fdisk -l # Ascertain the partitioning scheme.
sabayon sabayonuser # mkdir /mnt/mychroot
sabayon sabayonuser # mount /dev/sda2 /mnt/mychroot
sabayon sabayonuser # mount --rbind /dev /mnt/mychroot/dev
sabayon sabayonuser # mount --make-rslave /mnt/mychroot/dev
sabayon sabayonuser # mount -t proc /proc /mnt/mychroot/proc
sabayon sabayonuser # mount --rbind /sys /mnt/mychroot/sys
sabayon sabayonuser # mount --make-rslave /mnt/mychroot/sys
sabayon sabayonuser # mount --rbind /tmp /mnt/mychroot/tmp
sabayon sabayonuser # chroot /mnt/mychroot /bin/bash
sabayon / # source /etc/profile
sabayon / # env-update
>>> Regenerating /etc/ld.so.cache...
sabayon / # export PS1="(chroot) $PS1"
(chroot) sabayon / #

Now you can enter whatever commands you want in the chrooted environment. When you have finished, exit the chroot as follows:

(chroot) sabayon / # exit
exit
sabayon sabayonuser # umount -R /mnt/mychroot/tmp /mnt/mychroot/sys /mnt/mychroot/proc /mnt/mychroot/dev /mnt/mychroot
sabayon sabayonuser # shutdown -h now

Example 2: Sabayon Linux was installed in a logical volume

Let’s say, for example, that the installation has three partitions: /dev/sda1 (EFI System Partition formatted with FAT32); /dev/sda2 (/boot partition formatted with ext4); /dev/sda3 as the LVM Physical Volume with Volume Group sabayon_sabayon containing Logical Volumes root (formatted as ext4) and swap (linuxswap). Modify the mount commands accordingly if the structure is different in your case. In this example, /boot is not on the same partition as root (/) and therefore needs to be mounted separately.

Boot a Sabayon Linux LiveDVD or LivePenDrive, open a terminal window and enter the following commands:

sabayonuser@sabayon ~ $ su
sabayon sabayonuser # fdisk -l # Ascertain the partitioning scheme.
sabayon sabayonuser # pvdisplay
  --- Physical volume ---
  PV Name               /dev/sda3
  VG Name               sabayon_sabayon
  PV Size               39.31 GiB / not usable 2.00 MiB
  Allocatable           yes 
  PE Size               4.00 MiB
  Total PE              10064
  Free PE               1
  Allocated PE          10063
  PV UUID               489QRE-rvgD-JUXz-ZYad-1DM7-XNwr-lDFVNw

sabayon sabayonuser # vgdisplay
  --- Volume group ---
  VG Name               sabayon_sabayon
  System ID             
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  3
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                2
  Open LV               0
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               39.31 GiB
  PE Size               4.00 MiB
  Total PE              10064
  Alloc PE / Size       10063 / 39.31 GiB
  Free  PE / Size       1 / 4.00 MiB
  VG UUID               oZ2s2c-fm35-VBCT-ef3i-n8OJ-79a2-IOJ5iW

sabayon sabayonuser # lvdisplay
  --- Logical volume ---
  LV Path                /dev/sabayon_sabayon/swap
  LV Name                swap
  VG Name                sabayon_sabayon
  LV UUID                dNoMjX-yv7i-3UVR-vG2s-jsJG-PHfX-BvCYs9
  LV Write Access        read/write
  LV Creation host, time sabayon, 2018-01-05 22:55:16 +0000
  LV Status              available
  # open                 0
  LV Size                2.00 GiB
  Current LE             512
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           251:0
   
  --- Logical volume ---
  LV Path                /dev/sabayon_sabayon/root
  LV Name                root
  VG Name                sabayon_sabayon
  LV UUID                Lf81Ni-LfMu-Pifu-UUzl-ypKK-xSUc-pPfawz
  LV Write Access        read/write
  LV Creation host, time sabayon, 2018-01-05 22:55:17 +0000
  LV Status              available
  # open                 0
  LV Size                37.31 GiB
  Current LE             9551
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           251:1

sabayon sabayonuser # pvscan
File descriptor 16 (socket:[30370]) leaked on pvscan invocation. Parent PID 2635: bash
  PV /dev/sda3   VG sabayon_sabayon   lvm2 [39.31 GiB / 4.00 MiB free]
  Total: 1 [39.31 GiB] / in use: 1 [39.31 GiB] / in no VG: 0 [0   ]
sabayon sabayonuser # vgscan
File descriptor 16 (socket:[30370]) leaked on vgscan invocation. Parent PID 2635: bash
  Reading volume groups from cache.
  Found volume group "sabayon_sabayon" using metadata type lvm2
sabayon sabayonuser # vgchange -ay
File descriptor 16 (socket:[30370]) leaked on vgchange invocation. Parent PID 2635: bash
  2 logical volume(s) in volume group "sabayon_sabayon" now active
sabayon sabayonuser # lvscan
File descriptor 16 (socket:[30370]) leaked on lvscan invocation. Parent PID 2635: bash
  ACTIVE            '/dev/sabayon_sabayon/swap' [2.00 GiB] inherit
  ACTIVE            '/dev/sabayon_sabayon/root' [37.31 GiB] inherit
sabayon sabayonuser # mkdir /mnt/mychroot
sabayon sabayonuser # mount /dev/sabayon_sabayon/root /mnt/mychroot
sabayon sabayonuser # mount /dev/sda2 /mnt/mychroot/boot
sabayon sabayonuser # mount --rbind /dev /mnt/mychroot/dev
sabayon sabayonuser # mount --make-rslave /mnt/mychroot/dev
sabayon sabayonuser # mount -t proc /proc /mnt/mychroot/proc
sabayon sabayonuser # mount --rbind /sys /mnt/mychroot/sys
sabayon sabayonuser # mount --make-rslave /mnt/mychroot/sys
sabayon sabayonuser # mount --rbind /tmp /mnt/mychroot/tmp
sabayon sabayonuser # chroot /mnt/mychroot /bin/bash
sabayon / # source /etc/profile
sabayon / # env-update
>>> Regenerating /etc/ld.so.cache...
sabayon / # export PS1="(chroot) $PS1"
(chroot) sabayon / #

Now you can enter whatever commands you want in the chrooted environment. For example:

(chroot) sabayon / # equo version
319

When you have finished, exit the chroot as follows:

(chroot) sabayon / # exit
exit
sabayon sabayonuser # umount -R /mnt/mychroot/tmp /mnt/mychroot/sys /mnt/mychroot/proc /mnt/mychroot/dev /mnt/mychroot/boot /mnt/mychroot
sabayon sabayonuser # equo version
310
sabayon sabayonuser # shutdown -h now

In the example above I have used the ‘equo version‘ command in the chroot environment and in the LiveDVD environment, simply to illustrate that the two environments are not the same. As you can see, the LiveDVD I used has the package equo-310 installed, whereas the installation on the HDD has equo-319 installed.

By the way, if using the Sabayon Linux KDE LiveDVD/LivePenDrive, I discovered that the LVM command ‘vgchange -ay‘ can be omitted if I launch the KDE Partition Manager:

sabayon sabayonuser # partitionmanager

I just look at the partitions in the KDE Partition Manager’s GUI and quit the application (‘File’ > ‘Quit’).

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