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@prashantvidja
Created January 1, 2020 18:56
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Shrink raspberry pi image
#!/bin/bash
version="v0.1.2"
CURRENT_DIR=$(pwd)
SCRIPTNAME="${0##*/}"
LOGFILE=${CURRENT_DIR}/${SCRIPTNAME%.*}.log
function info() {
echo "$SCRIPTNAME: $1..."
}
function error() {
echo -n "$SCRIPTNAME: ERROR occured in line $1: "
shift
echo "$@"
}
function cleanup() {
if losetup "$loopback" &>/dev/null; then
losetup -d "$loopback"
fi
if [ "$debug" = true ]; then
local old_owner=$(stat -c %u:%g "$src")
chown "$old_owner" "$LOGFILE"
fi
}
function logVariables() {
if [ "$debug" = true ]; then
echo "Line $1" >> "$LOGFILE"
shift
local v var
for var in "$@"; do
eval "v=\$$var"
echo "$var: $v" >> "$LOGFILE"
done
fi
}
function checkFilesystem() {
info "Checking filesystem"
e2fsck -pf "$loopback"
(( $? < 4 )) && return
info "Filesystem error detected!"
info "Trying to recover corrupted filesystem"
e2fsck -y "$loopback"
(( $? < 4 )) && return
if [[ $repair == true ]]; then
info "Trying to recover corrupted filesystem - Phase 2"
e2fsck -fy -b 32768 "$loopback"
(( $? < 4 )) && return
fi
error $LINENO "Filesystem recoveries failed. Giving up..."
exit -9
}
help() {
local help
read -r -d '' help << EOM
Usage: $0 [-sdrpzh] imagefile.img [newimagefile.img]
-s: Don't expand filesystem when image is booted the first time
-d: Write debug messages in a debug log file
-r: Use advanced filesystem repair option if the normal one fails
-z: Gzip compress image after shrinking
EOM
echo "$help"
exit -1
}
usage() {
echo "Usage: $0 [-sdrpzh] imagefile.img [newimagefile.img]"
echo ""
echo " -s: Skip autoexpand"
echo " -d: Debug mode on"
echo " -r: Use advanced repair options"
echo " -z: Gzip compress image after shrinking"
echo " -h: display help text"
exit -1
}
should_skip_autoexpand=false
debug=false
repair=false
gzip_compress=false
while getopts ":sdrzh" opt; do
case "${opt}" in
s) should_skip_autoexpand=true ;;
d) debug=true;;
r) repair=true;;
z) gzip_compress=true;;
h) help;;
*) usage ;;
esac
done
shift $((OPTIND-1))
if [ "$debug" = true ]; then
info "Creating log file $LOGFILE"
rm "$LOGFILE" &>/dev/null
exec 1> >(stdbuf -i0 -o0 -e0 tee -a "$LOGFILE" >&1)
exec 2> >(stdbuf -i0 -o0 -e0 tee -a "$LOGFILE" >&2)
fi
echo "${0##*/} $version"
#Args
src="$1"
img="$1"
#Usage checks
if [[ -z "$img" ]]; then
usage
fi
if [[ ! -f "$img" ]]; then
error $LINENO "$img is not a file..."
exit -2
fi
if (( EUID != 0 )); then
error $LINENO "You need to be running as root."
exit -3
fi
#Check that what we need is installed
for command in parted losetup tune2fs md5sum e2fsck resize2fs; do
command -v $command >/dev/null 2>&1
if (( $? != 0 )); then
error $LINENO "$command is not installed."
exit -4
fi
done
#Copy to new file if requested
if [ -n "$2" ]; then
info "Copying $1 to $2..."
cp --reflink=auto --sparse=always "$1" "$2"
if (( $? != 0 )); then
error $LINENO "Could not copy file..."
exit -5
fi
old_owner=$(stat -c %u:%g "$1")
chown "$old_owner" "$2"
img="$2"
fi
# cleanup at script exit
trap cleanup ERR EXIT
#Gather info
info "Gatherin data"
beforesize=$(ls -lh "$img" | cut -d ' ' -f 5)
parted_output=$(parted -ms "$img" unit B print | tail -n 1)
partnum=$(echo "$parted_output" | cut -d ':' -f 1)
partstart=$(echo "$parted_output" | cut -d ':' -f 2 | tr -d 'B')
loopback=$(losetup -f --show -o "$partstart" "$img")
tune2fs_output=$(tune2fs -l "$loopback")
currentsize=$(echo "$tune2fs_output" | grep '^Block count:' | tr -d ' ' | cut -d ':' -f 2)
blocksize=$(echo "$tune2fs_output" | grep '^Block size:' | tr -d ' ' | cut -d ':' -f 2)
logVariables $LINENO tune2fs_output currentsize blocksize
#Check if we should make pi expand rootfs on next boot
if [ "$should_skip_autoexpand" = false ]; then
#Make pi expand rootfs on next boot
mountdir=$(mktemp -d)
mount "$loopback" "$mountdir"
if [ "$(md5sum "$mountdir/etc/rc.local" | cut -d ' ' -f 1)" != "0542054e9ff2d2e0507ea1ffe7d4fc87" ]; then
echo "Creating new /etc/rc.local"
mv "$mountdir/etc/rc.local" "$mountdir/etc/rc.local.bak"
#####Do not touch the following lines#####
cat <<\EOF1 > "$mountdir/etc/rc.local"
#!/bin/bash
do_expand_rootfs() {
ROOT_PART=$(mount | sed -n 's|^/dev/\(.*\) on / .*|\1|p')
PART_NUM=${ROOT_PART#mmcblk0p}
if [ "$PART_NUM" = "$ROOT_PART" ]; then
echo "$ROOT_PART is not an SD card. Don't know how to expand"
return 0
fi
# Get the starting offset of the root partition
PART_START=$(parted /dev/mmcblk0 -ms unit s p | grep "^${PART_NUM}" | cut -f 2 -d: | sed 's/[^0-9]//g')
[ "$PART_START" ] || return 1
# Return value will likely be error for fdisk as it fails to reload the
# partition table because the root fs is mounted
fdisk /dev/mmcblk0 <<EOF
p
d
$PART_NUM
n
p
$PART_NUM
$PART_START
p
w
EOF
cat <<EOF > /etc/rc.local &&
#!/bin/sh
echo "Expanding /dev/$ROOT_PART"
resize2fs /dev/$ROOT_PART
rm -f /etc/rc.local; cp -f /etc/rc.local.bak /etc/rc.local; /etc/rc.local
EOF
reboot
exit
}
raspi_config_expand() {
/usr/bin/env raspi-config --expand-rootfs
if [[ $? != 0 ]]; then
return -1
else
rm -f /etc/rc.local; cp -f /etc/rc.local.bak /etc/rc.local; /etc/rc.local
reboot
exit
fi
}
raspi_config_expand
echo "WARNING: Using backup expand..."
sleep 5
do_expand_rootfs
echo "ERROR: Expanding failed..."
sleep 5
rm -f /etc/rc.local; cp -f /etc/rc.local.bak /etc/rc.local; /etc/rc.local
exit 0
EOF1
#####End no touch zone#####
chmod +x "$mountdir/etc/rc.local"
fi
umount "$mountdir"
else
echo "Skipping autoexpanding process..."
fi
#Make sure filesystem is ok
checkFilesystem
if ! minsize=$(resize2fs -P "$loopback"); then
rc=$?
error $LINENO "resize2fs failed with rc $rc"
exit -10
fi
minsize=$(cut -d ':' -f 2 <<< "$minsize" | tr -d ' ')
logVariables $LINENO minsize
if [[ $currentsize -eq $minsize ]]; then
error $LINENO "Image already shrunk to smallest size"
exit -11
fi
#Add some free space to the end of the filesystem
extra_space=$(($currentsize - $minsize))
logVariables $LINENO extra_space
for space in 5000 1000 100; do
if [[ $extra_space -gt $space ]]; then
minsize=$(($minsize + $space))
break
fi
done
logVariables $LINENO minsize
#Shrink filesystem
info "Shrinking filesystem"
resize2fs -p "$loopback" $minsize
if [[ $? != 0 ]]; then
error $LINENO "resize2fs failed"
mount "$loopback" "$mountdir"
mv "$mountdir/etc/rc.local.bak" "$mountdir/etc/rc.local"
umount "$mountdir"
losetup -d "$loopback"
exit -12
fi
sleep 1
#Shrink partition
partnewsize=$(($minsize * $blocksize))
newpartend=$(($partstart + $partnewsize))
logVariables $LINENO partnewsize newpartend
if ! parted -s -a minimal "$img" rm "$partnum"; then
rc=$?
error $LINENO "parted failed with rc $rc"
exit -13
fi
if ! parted -s "$img" unit B mkpart primary "$partstart" "$newpartend"; then
rc=$?
error $LINENO "parted failed with rc $rc"
exit -14
fi
#Truncate the file
info "Shrinking image"
if ! endresult=$(parted -ms "$img" unit B print free); then
rc=$?
error $LINENO "parted failed with rc $rc"
exit -15
fi
endresult=$(tail -1 <<< "$endresult" | cut -d ':' -f 2 | tr -d 'B')
logVariables $LINENO endresult
if ! truncate -s "$endresult" "$img"; then
rc=$?
error $LINENO "trunate failed with rc $rc"
exit -16
fi
if [[ $gzip_compress == true ]]; then
info "Gzipping the shrunk image"
if [[ ! $(gzip -f9 "$img") ]]; then
img=$img.gz
fi
fi
aftersize=$(ls -lh "$img" | cut -d ' ' -f 5)
logVariables $LINENO aftersize
info "Shrunk $img from $beforesize to $aftersize"
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