Can't log into arch and pacman won't open following a botched update, need to recover data

Question

Highlighted Info - For quick reply

• Attempting to enter a username to Arch Linux results in Login failed. and no reply to input a user's password.
• Arch-chrooting into the partitions ends up with pacman responding with error while loading shared libraries: libgsap_krb5.so.2: cannot open shared object file: No such file or directory
• Attempting to view /home/nature results in one file being returned within the directory "install_pacaur.sh" which is the file I used when setting up Arch.
• Data recovery seems to be impossible (according to my knowledge) unless I am able to login to the OS and mount a vfat formated USB. (I need to recover two .odt documents)
• I only need to recover files from my home partition; the OS is unimportant.

What happened

Earlier today I was updating my laptop's Arch packages and for some reason a few packages were deleted, missing, or corrupt. The following packages were maintained by Levente Polyak on the Arch repository: krb5, jasper, libpsl, and etcetera. I can not determine how many packages were effected on my system, but I assume a minuscule amount of somewhere around 5.

Issue

Due to this mishap, my computer seems not to function and every time a username is entered the computer returns Login failed.. I assume this issue has to do with krb5. Furthermore upon arch-chrooting into the partitions and mounting, pacman does not work and results with the follow output: pacman: error while loading shared libraries: libgsap_krb5.so.2: cannot open shared object file: No such file or directory.

Any help would be graciously appreciated as I have some valuable notes stored on my laptop that need to be recovered. (These were taken in the last week, so I had not backed up to the cloud yet.) The notes are needed for an exam I am having tomorrow, so any reply is graciously appreciated. I will take this instance to only use Arch for my home desktop and switch my laptop to a more stable OS.

edit: Please let me know if any further information is required.

Answer 1

First, since you seem to already have a rescue medium available, use it to reinstall the broken packages: assuming the rootfs is mounted on /mnt,

pacman -r /mnt -Syu krb5
 - or -
pacstrap /mnt krb5

will reinstall the broken package without needing a chroot. Afterwards do a package check to find out what other packages, if any, are missing their files:

pacman -r /mnt -Qqkk

and reinstall those using pacman -r … as well.

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Second, from the looks of it, you have a separate /home partition – so you'll have to actually mount it first before trying to access your files.

Check /mnt/etc/fstab or run lsblk or lsblk -f to see which partition it is.