PiShrink/pishrink.sh

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#!/bin/bash
usage() { echo "Usage: $0 [-s] imagefile.img [newimagefile.img]"; exit -1; }
should_skip_autoexpand=false
while getopts ":s" opt; do
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case "${opt}" in
s) should_skip_autoexpand=true ;;
*) usage ;;
esac
done
shift $((OPTIND-1))
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#Args
img=$1
#Usage checks
if [[ -z $img ]]; then
usage
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fi
if [[ ! -e $img ]]; then
echo "ERROR: $img is not a file..."
exit -2
fi
if (( EUID != 0 )); then
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echo "ERROR: You need to be running as root."
exit -3
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fi
#Check that what we need is installed
A=`which parted 2>&1`
if (( $? != 0 )); then
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echo "ERROR: parted is not installed."
exit -4
fi
#Copy to new file if requested
if [ -n "$2" ]; then
echo "Copying $1 to $2..."
cp --reflink=auto --sparse=always "$1" "$2"
if (( $? != 0 )); then
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echo "ERROR: Could not copy file..."
exit -5
fi
img=$2
fi
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#Gather info
beforesize=`ls -lah $img | cut -d ' ' -f 5`
partnum=`parted -m $img unit B print | tail -n 1 | cut -d ':' -f 1 | tr -d '\n'`
partstart=`parted -m $img unit B print | tail -n 1 | cut -d ':' -f 2 | tr -d 'B\n'`
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loopback=`losetup -f --show -o $partstart $img`
currentsize=`tune2fs -l $loopback | grep 'Block count' | tr -d ' ' | cut -d ':' -f 2 | tr -d '\n'`
blocksize=`tune2fs -l $loopback | grep 'Block size' | tr -d ' ' | cut -d ':' -f 2 | tr -d '\n'`
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#Check if we should make pi expand rootfs on next boot
if [ "$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` != "c4eb22d9aa99915af319287d194d4529" ]; then
echo Creating new /etc/rc.local
mv $mountdir/etc/rc.local $mountdir/etc/rc.local.bak
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###Do not touch the following 6 lines including EOF###
cat <<\EOFE > $mountdir/etc/rc.local
#!/bin/bash
do_expand_rootfs() {
ROOT_PART=$(cat /proc/cmdline | tr -s ' ' '\n' | grep root= | cut -d '=' -f 2)
if [[ "$ROOT_PART" != /dev/mmcblk0* ]] ; then
echo $ROOT_PART is not an SD card...
return 0
fi
PART_NUM=$(echo $ROOT_PART | cut -d 'p' -f 2)
# Get the starting offset of the root partition
PART_START=$(fdisk -l /dev/mmcblk0 | grep $ROOT_PART | tr -s ' ' | cut -d ' ' -f 2)
[ "$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
w
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EOF
cat <<EOF > /etc/rc.local &&
#!/bin/sh
resize2fs $ROOT_PART
rm -f /etc/rc.local; cp -f /etc/rc.local.bak /etc/rc.local; /etc/rc.local
EOF
reboot
exit
}
do_expand_rootfs
rm -f /etc/rc.local; cp -f /etc/rc.local.bak /etc/rc.local; /etc/rc.local
exit 0
EOFE
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###End no touch zone###
chmod +x $mountdir/etc/rc.local
fi
umount $mountdir
else
echo Skipping autoexpanding process...
fi
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#Make sure filesystem is ok
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e2fsck -f $loopback
minsize=`resize2fs -P $loopback | cut -d ':' -f 2 | tr -d ' ' | tr -d '\n'`
if [[ $currentsize -eq $minsize ]]; then
echo ERROR: Image already shrunk to smallest size
exit -6
fi
#Add some free space to the end of the filesystem
if [[ `expr $currentsize - $minsize - 5000` -gt 0 ]]; then
minsize=`expr $minsize + 5000 | tr -d '\n'`
elif [[ `expr $currentsize - $minsize - 1000` -gt 0 ]]; then
minsize=`expr $minsize + 1000 | tr -d '\n'`
elif [[ `expr $currentsize - $minsize - 100` -gt 0 ]]; then
minsize=`expr $minsize + 100 | tr -d '\n'`
fi
#Shrink filesystem
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resize2fs -p $loopback $minsize
if [[ $? != 0 ]]; then
echo ERROR: resize2fs failed...
mount $loopback $mountdir
mv $mountdir/etc/rc.local.bak $mountdir/etc/rc.local
umount $mountdir
losetup -d $loopback
exit $rc
fi
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sleep 1
#Shrink partition
losetup -d $loopback
partnewsize=`expr $minsize \* $blocksize | tr -d '\n'`
newpartend=`expr $partstart + $partnewsize | tr -d '\n'`
part1=`parted $img rm $partnum`
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part2=`parted $img unit B mkpart primary $partstart $newpartend`
#Truncate the file
endresult=`parted -m $img unit B print free | tail -1 | cut -d ':' -f 2 | tr -d 'B\n'`
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truncate -s $endresult $img
aftersize=`ls -lah $img | cut -d ' ' -f 5`
echo "Shrunk $img from $beforesize to $aftersize"