Script for converting Fedora LiveCD to LiveUSB with persistence

fedora_to_usb.sh

#!/bin/bash
# Script for converting Fedora (and maybe other dracut-based) LiveCD to LiveUSB
# with persistence. Only UEFI boot supported. Tested with Fedora 37.
#
# Usage:
#     ./fedora_to_usb.sh path/to/mounted/livecd /dev/sdX
#
# Result USB partitioning:
#   GPT, 2 partitions:
#     - "EFI" (vfat 256MB) for GRUB and kernel
#     - "EXT" (ext4 rest of USB device) for SquashFS, OverlayFS and "updates"
#
# Expected LiveCD content:
#   - boot      -> for BIOS boot, ignored
#   - EFI       -> copy to EFI part 
#   - Fedora-Legal-README.txt -> ignored
#   - images    -> copy to EFI part 
#   - LICENSE   -> ignored
#   - LiveOS    -> copy to EXT part
#
# Persistence:
#   - EXT:/overlayfs contains files diff to SquashFS, saved automatically
#   - EXT:/updates contains files to copy to root at every boot, filled manually
#
# Configuration:  
#   - EFI:/EFI/BOOT/grub.cfg patched, editable grub cfg. Original moved to .bak 
#       - rd.live.overlay.readonly=0 and rd.live.overlay.reset=0 can be changed 
#         before boot in grub menu with "e" key.
#   - EXT:/updates can be used to provide pre-config for SquashFS.
#       - etc/fstab, symlinks for systemd services(to /dev/null for disable),
#         binaries, sshd_config, etc.
#
# Example:
#
# updates
# ├── etc
# │     ├── fstab
# │     ├── NetworkManager
# │     │     └── system-connections
# │     │         ├── wifi1.nmconnection
# │     │         └── wifi2.nmconnection
# │     ├── ssh
# │     │     ├── sshd_config.d
# │     │     │     └── 51-root.conf
# │     │     ├── ssh_host_ecdsa_key
# │     │     ├── ssh_host_ecdsa_key.pub
# │     │     ├── ssh_host_ed25519_key
# │     │     ├── ssh_host_ed25519_key.pub
# │     │     ├── ssh_host_rsa_key
# │     │     └── ssh_host_rsa_key.pub
# │     ├── systemd
# │     │     └── system
# │     │         ├── bluetooth.target.wants
# │     │         │     └── bluetooth.service -> /dev/null
# │     │         ├── dbus-org.bluez.service -> /dev/null
# │     │         ├── dbus-org.fedoraproject.FirewallD1.service -> /dev/null
# │     │         ├── graphical.target.wants
# │     │         │     └── upower.service -> /dev/null
# │     │         ├── multi-user.target.wants
# │     │         │     ├── abrtd.service -> /dev/null
# │     │         │     ├── atd.service -> /dev/null
# │     │         │     ├── auditd.service -> /dev/null
# │     │         │     ├── chronyd.service -> /dev/null
# │     │         │     ├── crond.service -> /dev/null
# │     │         │     ├── cups.path -> /dev/null
# │     │         │     ├── firewalld.service -> /dev/null
# │     │         │     ├── mdmonitor.service -> /dev/null
# │     │         │     ├── smartd.service -> /dev/null
# │     │         │     └── sshd.service -> /usr/lib/systemd/system/sshd.service
# │     │         ├── sockets.target.wants
# │     │         │     └── cups.socket -> /dev/null
# │     │         └── sysinit.target.wants
# │     │             └── dmraid-activation.service -> /dev/null
# │     └── xdg
# │         └── autostart
# │             ├── clipit-startup.desktop -> /dev/null
# │             ├── geoclue-demo-agent.desktop -> /dev/null
# │             ├── liveinst-setup.desktop -> /dev/null
# │             ├── org.mageia.dnfdragora-updater.desktop -> /dev/null
# │             └── xscreensaver-autostart.desktop -> /dev/null
# ├── mnt
# │     ├── efi
# │     └── ext -> /run/initramfs/live
# └── usr
#      └── bin
#           └── htop
#
# fstab:
# vartmp    /var/tmp    tmpfs   defaults   0  0
# tmpfs     /var/log    tmpfs   defaults   0  0
# tmpfs     /var/cache  tmpfs   defaults   0  0
# LABEL=EFI /mnt/efi    vfat    defaults   0  0
#
# find_replace_null.sh: find "deleted" files in dir and replace with symlinks to 
#                       /dev/null, usable after copy from overlayfs to updates
# find $1 -perm 0 -print -exec rm {} \; -exec ln -s /dev/null {} \;

if [ $# -ne 2 ] ; then
	echo "ERROR : bad arguments, read script header for manual."
	echo $0 SRCDIR USBDEV
	exit 1
fi

SRCDIR=$1
USBDEV=$2
LABEL_EFI="EFI"
LABEL_EXT="EXT"

cleanup() {
	local RC=$?
	[ $RC -ne 0 ] && echo "ERROR or ABORT detected ! Doing cleanup and exit (may take some time)."
	umount $MNT 2>/dev/null
	rmdir $MNT 2>/dev/null
	return $RC
}
trap cleanup EXIT

USBDEVP1="${USBDEV}1"
USBDEVP2="${USBDEV}2"
MNT=$(mktemp -d)
echo Temp mount point $MNT

echo fdisk $USBDEV
echo '
g
n


+256M
t
C12A7328-F81F-11D2-BA4B-00A0C93EC93B
n



t

0FC63DAF-8483-4772-8E79-3D69D8477DE4
p
w
' | \
	fdisk $USBDEV

echo mkdosfs $USBDEVP1
mkdosfs -v -F32 -n $LABEL_EFI $USBDEVP1
echo Mount $USBDEVP1 to $MNT
mount $USBDEVP1 $MNT
echo Copy EFI and kernel
cp -ar $SRCDIR/EFI $MNT/
cp -ar $SRCDIR/images $MNT/
echo Patch GRUB config
mv $MNT/EFI/BOOT/grub.cfg $MNT/EFI/BOOT/grub.cfg.bak
echo "$(
	cat <<EOF
set LABEL_EFI="$LABEL_EFI"
set LABEL_EXT="$LABEL_EXT"
set EXTRA_ARGS="plymouth.enable=0 disablehooks=plymouth audit=0 selinux=0"
set KERNEL_ARGS="root=live:LABEL=\$LABEL_EXT rw rd.live.image rd.live.overlay.overlayfs rd.live.overlay=LABEL=\$LABEL_EXT:/overlayfs \$EXTRA_ARGS"
EOF
) 

$(cat $MNT/EFI/BOOT/grub.cfg.bak | \
	sed 's/set default=.*/set default=0/' | \
	sed 's/set timeout=.*/set timeout=1/' | \
	sed 's/quiet//'        | \
	sed 's/rhgb//'         | \
	sed 's/rd.live.image//'| \
	sed 's/search .*/search --no-floppy --set=root -l \$LABEL_EFI/' | \
	sed 's/root=live:CDLABEL=[^ ]*/$KERNEL_ARGS rd.live.overlay.readonly=0 rd.live.overlay.reset=0/')" > $MNT/EFI/BOOT/grub.cfg
diff $MNT/EFI/BOOT/grub.cfg.bak $MNT/EFI/BOOT/grub.cfg
echo Umount $MNT
umount $MNT

echo mkfs.ext4 $USBDEVP2
mkfs.ext4 -F -L $LABEL_EXT -O ^64bit -j $USBDEVP2
tune2fs -c0 -i0 -ouser_xattr,acl $USBDEVP2
echo Mount $USBDEVP2 to $MNT
mount $USBDEVP2 $MNT
echo Copy LiveOS
cp -ar $SRCDIR/LiveOS $MNT/
echo Make overlay and updates dirs
mkdir -m 0755 $MNT/updates $MNT/overlayfs $MNT/ovlwork
echo Umount $MNT
umount $MNT