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Currently, the MBR on my machine is corrupted, so I decide to re-install GRUB from a liveCD and with chroot. From this tutorial, I can complete the re-installation. However, I'm not clear about the reason why I should mount /proc on the new root environment. (For /dev and /sys I think it is because some files should be referred.) Is the same reason for /proc, which files on /proc are required when re-installing GRUB?

Thanks and Best Regards!

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up vote 1 down vote accepted

/proc is a virtual file system that contains pretty specific information regarding the system, stuff like environmental variables and hardware setup. So it is required for kernel specific information during chroot use (for example, lsmod is closely tied with /proc/modules).

Gentoo gives a very minimal summary in their handbook

To make sure that the new environment works properly, 
we need to make certain file systems available there as well.

Mount the /proc filesystem on /mnt/gentoo/proc to allow 
the installation to use the kernel-provided information 
within the chrooted environment, …

It's mostly system information, so it likely provides that GRUB may need in the process, such as things in /proc/sys, which provides for scripts to be run on boot (may be involved with GRUB, I am not sure there).

If you want to get really in-depth with what /proc does and contains, perhaps this will be a good read.

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Thank you for the link. – Summer_More_More_Tea Jan 19 '13 at 2:12

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