(Arch Linux) Keep current modules around during kernel upgrade

⁄etc⁄pacman.d⁄hooks⁄linux-modules-post.hook

[Trigger]
Operation = Upgrade
Type = Package
Target = linux

[Action]
Description = Restore Linux kernel modules
When = PostTransaction
Depends = coreutils
Depends = rsync
Exec = /bin/sh -xc 'KVER="${KVER:-$(uname -r)}"; if test -e "/lib/modules/backup/${KVER}"; then rsync -AHXal --ignore-existing "/lib/modules/backup/${KVER}" /lib/modules/; fi; rm -rf /lib/modules/backup'

⁄etc⁄pacman.d⁄hooks⁄linux-modules-pre.hook

[Trigger]
Operation = Upgrade
Type = Package
Target = linux

[Action]
Description = Save Linux kernel modules
When = PreTransaction
Depends = rsync
Exec = /bin/sh -c 'KVER="${KVER:-$(uname -r)}"; if test -e "/lib/modules/${KVER}"; then rsync -AHXal --delete-after "/lib/modules/${KVER}" /lib/modules/backup/; fi'

⁄etc⁄systemd⁄system⁄linux-modules-cleanup.service

[Unit]
Description=Clean up modules from old kernels

[Service]
Type=oneshot
ExecStart=/bin/bash -exc 'for i in /usr/lib/modules/[0-9]*; do if [[ $${i##*/} = \'%v\' ]] || pacman -Qo "$${i}"; then continue; fi; rsync -AHXal "$${i}" /usr/lib/modules/.old/; rm -rf "$${i}"; done'

[Install]
WantedBy=basic.target

⁄etc⁄tmpfiles.d⁄linux-modules-cleanup.conf

R! /usr/lib/modules/.old/* - - - 4w

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