Why bind to LiveCD /proc before building initramfs ? Post: 303001642

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Top Forums UNIX for Beginners Questions & Answers Why bind to LiveCD /proc before building initramfs ? Post 303001642 by Corona688 on Tuesday 8th of August 2017 11:29:22 AM

08-08-2017

Registered User

Quote:

Originally Posted by sreyan32

Imagine I have an unbootable system where I need to update the kernel image using

Code:

update-initramfs

.

I have seen numerous examples online which show the following

Code:

$ mount -t proc none /mnt/ubuntu/proc
$ mount -o bind /dev /mnt/ubuntu/dev
$ mount -o bind /sys /mnt/ubuntu/sys

After that we chroot into the broken OS and then execute the command to update the initramfs.

My questions are as follows-:
[LIST=1][*]Are we binding the /proc and /dev of the Live CD to the broken system ? Or are we binding the /proc and /dev of the broken system to the live cd ?

Neither. /dev and especially /proc are virtual filesystems, which don't show files but rather imaginary kernel things.

So they're neither livecd, nor your broken system, but something belonging to whatever kernel you're running.

These kernel / device interfaces are pretty hard for a system to do without.

Quote:

If building the initramfs is dependent on the information of the OS for which the initramfs is built then won't it contain erroneous information if we build for the Live CD ? That is use the /proc and /dev of the LiveCD ?

It doesn't so much archive them as use them.

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ltsp-chroot

ltsp-chroot(8)															    ltsp-chroot(8)

NAME

       ltsp-chroot - Chroots into a specific LTSP thin client chroot

SYNOPSIS

       ltsp-chroot  <options>

DESCRIPTION

       ltsp-chroot  chroots  into  a  specified  LTSP chroot. Optional arguments can be provided to customize the chroot location as well as extra
       mounts.	If present, default arguments will be read from the configuration file /etc/ltsp/ltsp-chroot.conf, and overwritten with used  com-
       mand line options.

OPTIONS

       -a --arch arch
		 Sets the architecture of the target chroot. Defaults vary by distribution.

       -b --base dir
		 Sets the path of the target chroot. Defaults to /opt/ltsp/.

       -c --mount-package-cache
		 If set, mounts the server package directories to the chroot previous to chrooting. Settings vary by distribution.

       -d --mount-dev
		 If set, mounts the server dev and devpts directories to the chroot previous to chrooting.

       -p --mount-proc
		 If set, mounts the server proc to the chroot previous to chrooting.

       -m --mount-all
		 If set, mounts the proc, dev and package directories to the chroot before chrooting.

       -p --copy-resolv-conf
		 If set, copies the server resolv.conf to the chroot previous to chrooting.

       -h --help Displays the ltsp-chroot help message.

SEE ALSO

       ltsp-build-client(8),

AVAILABILITY

       ltsp-chroot is part of ltsp package and the latest versions are available in source form from https://launchpad.net/products/ltsp.

MAN PAGE AUTHOR

       Wim Muskee <wimmmuskee@gmail.com>

								    2012-02-11							    ltsp-chroot(8)