PiShrink 是 Github 上开源的树莓派压缩工具，通过裁剪上面用 Win32DiskImager 或者 dd 命令全卡备份的镜像，去掉没有内容的分区，从而减小备份镜像的大小。

先将全卡备份的镜像文件复制到 Linux 中，打开终端执行wget https://raw.githubusercontent.com/Drewsif/PiShrink/master/pishrink.sh 下载 sh 脚本文件，默认存到/home/user目录下，将其拷贝到镜像所在文件夹下。执行chmod +x pishrink.sh 增加执行权限，然后执行sudo bash pishrink.sh rpi-back.img 即可。

pishrink.sh

#!/bin/bashversion="v0.1.2"CURRENT_DIR="$(pwd)"SCRIPTNAME="${0##*/}"MYNAME="${SCRIPTNAME%.*}"LOGFILE="${CURRENT_DIR}/${SCRIPTNAME%.*}.log"REQUIRED_TOOLS="parted losetup tune2fs md5sum e2fsck resize2fs"ZIPTOOLS=("gzip xz")declare -A ZIP_PARALLEL_TOOL=( [gzip]="pigz" [xz]="xz" ) # parallel zip tool to use in parallel modedeclare -A ZIP_PARALLEL_OPTIONS=( [gzip]="-f9" [xz]="-T0" ) # options for zip tools in parallel modedeclare -A ZIPEXTENSIONS=( [gzip]="gz" [xz]="xz" ) # extensions of zipped filesfunction info() { echo "$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 )) && returnif [[ $repair == true ]]; then info "Trying to recover corrupted filesystem - Phase 2" e2fsck -fy -b 32768 "$loopback" (( $? < 4 )) && returnfi error $LINENO "Filesystem recoveries failed. Giving up..." exit 9}function set_autoexpand() { #Make pi expand rootfs on next boot mountdir=$(mktemp -d) partprobe "$loopback" mount "$loopback" "$mountdir" if [ ! -d "$mountdir/etc" ]; then info "/etc not found, autoexpand will not be enabled" umount "$mountdir" return fi if [[ -f "$mountdir/etc/rc.local" ]] && [[ "$(md5sum "$mountdir/etc/rc.local" | cut -d ‘ ‘ -f 1)" != "1c579c7d5b4292fd948399b6ece39009" ]]; then echo "Creating new /etc/rc.local" if [ -f "$mountdir/etc/rc.local" ]; then mv "$mountdir/etc/rc.local" "$mountdir/etc/rc.local.bak" fi #####Do not touch the following lines#####cat <<\EOF1 > "$mountdir/etc/rc.local"#!/bin/bashdo_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‘) [ "$PART_START" ] || return 1 # Return value will likely be error for fdisk as it fails to reload the # partition table because the root fs is mounted fdisk /dev/mmcblk0 <<EOFpd$PART_NUMnp$PART_NUM$PART_STARTpwEOFcat <<EOF > /etc/rc.local &&#!/bin/shecho "Expanding /dev/$ROOT_PART"resize2fs /dev/$ROOT_PARTrm -f /etc/rc.local; cp -f /etc/rc.local.bak /etc/rc.local; /etc/rc.localEOFrebootexit}raspi_config_expand() {/usr/bin/env raspi-config --expand-rootfsif [[ $? != 0 ]]; then return -1else rm -f /etc/rc.local; cp -f /etc/rc.local.bak /etc/rc.local; /etc/rc.local reboot exitfi}raspi_config_expandecho "WARNING: Using backup expand..."sleep 5do_expand_rootfsecho "ERROR: Expanding failed..."sleep 5if [[ -f /etc/rc.local.bak ]]; then cp -f /etc/rc.local.bak /etc/rc.local /etc/rc.localfiexit 0EOF1 #####End no touch zone##### chmod +x "$mountdir/etc/rc.local" fi umount "$mountdir"}help() { local help read -r -d ‘‘ help << EOMUsage: $0 [-adhrspvzZ] imagefile.img [newimagefile.img] -s Don‘t expand filesystem when image is booted the first time -v Be verbose -r Use advanced filesystem repair option if the normal one fails -z Compress image after shrinking with gzip -Z Compress image after shrinking with xz -a Compress image in parallel using multiple cores -p Remove logs, apt archives, dhcp leases and ssh hostkeys -d Write debug messages in a debug log fileEOM echo "$help" exit 1}should_skip_autoexpand=falsedebug=falserepair=falseparallel=falseverbose=falseprep=falseziptool=""while getopts ":adhprsvzZ" opt; do case "${opt}" in a) parallel=true;; d) debug=true;; h) help;; p) prep=true;; r) repair=true;; s) should_skip_autoexpand=true ;; v) verbose=true;; z) ziptool="gzip";; Z) ziptool="xz";; *) help;; esacdoneshift $((OPTIND-1))if [ "$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)fiecho "${0##*/} $version"#Argssrc="$1"img="$1"#Usage checksif [[ -z "$img" ]]; then helpfiif [[ ! -f "$img" ]]; then error $LINENO "$img is not a file..." exit 2fiif (( EUID != 0 )); then error $LINENO "You need to be running as root." exit 3fi# check selected compression tool is supported and installedif [[ -n $ziptool ]]; then if [[ ! " ${ZIPTOOLS[@]} " =~ $ziptool ]]; then error $LINENO "$ziptool is an unsupported ziptool." exit 17 else if [[ $parallel == true && $ziptool == "gzip" ]]; then REQUIRED_TOOLS="$REQUIRED_TOOLS pigz" else REQUIRED_TOOLS="$REQUIRED_TOOLS $ziptool" fi fifi#Check that what we need is installedfor command in $REQUIRED_TOOLS; do command -v $command >/dev/null 2>&1 if (( $? != 0 )); then error $LINENO "$command is not installed." exit 4 fidone#Copy to new file if requestedif [ -n "$2" ]; then f="$2" if [[ -n $ziptool && "${f##*.}" == "${ZIPEXTENSIONS[$ziptool]}" ]]; then # remove zip extension if zip requested because zip tool will complain about extension f="${f%.*}" fi info "Copying $1 to $f..." cp --reflink=auto --sparse=always "$1" "$f" if (( $? != 0 )); then error $LINENO "Could not copy file..." exit 5 fi old_owner=$(stat -c %u:%g "$1") chown "$old_owner" "$f" img="$f"fi# cleanup at script exittrap cleanup EXIT#Gather infoinfo "Gathering data"beforesize="$(ls -lh "$img" | cut -d ‘ ‘ -f 5)"parted_output="$(parted -ms "$img" unit B print)"rc=$?if (( $rc )); then error $LINENO "parted failed with rc $rc" info "Possibly invalid image. Run ‘parted $img unit B print‘ manually to investigate" exit 6fipartnum="$(echo "$parted_output" | tail -n 1 | cut -d ‘:‘ -f 1)"partstart="$(echo "$parted_output" | tail -n 1 | cut -d ‘:‘ -f 2 | tr -d ‘B‘)"if [ -z "$(parted -s "$img" unit B print | grep "$partstart" | grep logical)" ]; then parttype="primary"else parttype="logical"filoopback="$(losetup -f --show -o "$partstart" "$img")"tune2fs_output="$(tune2fs -l "$loopback")"rc=$?if (( $rc )); then echo "$tune2fs_output" error $LINENO "tune2fs failed. Unable to shrink this type of image" exit 7ficurrentsize="$(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 $LINENO beforesize parted_output partnum partstart parttype tune2fs_output currentsize blocksize#Check if we should make pi expand rootfs on next bootif [ "$parttype" == "logical" ]; then echo "WARNING: PiShrink does not yet support autoexpanding of this type of image"elif [ "$should_skip_autoexpand" = false ]; then set_autoexpandelse echo "Skipping autoexpanding process..."fiif [[ $prep == true ]]; then info "Syspreping: Removing logs, apt archives, dhcp leases and ssh hostkeys" mountdir=$(mktemp -d) mount "$loopback" "$mountdir" rm -rf "$mountdir/var/cache/apt/archives/*" "$mountdir/var/lib/dhcpcd5/*" "$mountdir/var/log/*" "$mountdir/var/tmp/*" "$mountdir/tmp/*" "$mountdir/etc/ssh/*_host_*" umount "$mountdir"fi#Make sure filesystem is okcheckFilesystemif ! minsize=$(resize2fs -P "$loopback"); then rc=$? error $LINENO "resize2fs failed with rc $rc" exit 10fiminsize=$(cut -d ‘:‘ -f 2 <<< "$minsize" | tr -d ‘ ‘)logVariables $LINENO currentsize minsizeif [[ $currentsize -eq $minsize ]]; then error $LINENO "Image already shrunk to smallest size" exit 11fi#Add some free space to the end of the filesystemextra_space=$(($currentsize - $minsize))logVariables $LINENO extra_spacefor space in 5000 1000 100; do if [[ $extra_space -gt $space ]]; then minsize=$(($minsize + $space)) break fidonelogVariables $LINENO minsize#Shrink filesysteminfo "Shrinking filesystem"resize2fs -p "$loopback" $minsizerc=$?if (( $rc )); then error $LINENO "resize2fs failed with rc $rc" mount "$loopback" "$mountdir" mv "$mountdir/etc/rc.local.bak" "$mountdir/etc/rc.local" umount "$mountdir" losetup -d "$loopback" exit 12fisleep 1#Shrink partitionpartnewsize=$(($minsize * $blocksize))newpartend=$(($partstart + $partnewsize))logVariables $LINENO partnewsize newpartendparted -s -a minimal "$img" rm "$partnum"rc=$?if (( $rc )); then error $LINENO "parted failed with rc $rc" exit 13fiparted -s "$img" unit B mkpart "$parttype" "$partstart" "$newpartend"rc=$?if (( $rc )); then error $LINENO "parted failed with rc $rc" exit 14fi#Truncate the fileinfo "Shrinking image"endresult=$(parted -ms "$img" unit B print free)rc=$?if (( $rc )); then error $LINENO "parted failed with rc $rc" exit 15fiendresult=$(tail -1 <<< "$endresult" | cut -d ‘:‘ -f 2 | tr -d ‘B‘)logVariables $LINENO endresulttruncate -s "$endresult" "$img"rc=$?if (( $rc )); then error $LINENO "trunate failed with rc $rc" exit 16fi# handle compressionif [[ -n $ziptool ]]; then options="" envVarname="${MYNAME^^}_${ziptool^^}" # PISHRINK_GZIP or PISHRINK_XZ environment variables allow to override all options for gzip or xz [[ $parallel == true ]] && options="${ZIP_PARALLEL_OPTIONS[$ziptool]}" [[ -v $envVarname ]] && options="${!envVarname}" # if environment variable defined use these options [[ $verbose == true ]] && options="$options -v" # add verbose flag if requested if [[ $parallel == true ]]; then parallel_tool="${ZIP_PARALLEL_TOOL[$ziptool]}" info "Using $parallel_tool on the shrunk image" if ! $parallel_tool ${options} "$img"; then rc=$? error $LINENO "$parallel_tool failed with rc $rc" exit 18 fi else # sequential info "Using $ziptool on the shrunk image" if ! $ziptool ${options} "$img"; then rc=$? error $LINENO "$ziptool failed with rc $rc" exit 19 fi fi img=$img.${ZIPEXTENSIONS[$ziptool]}fiaftersize=$(ls -lh "$img" | cut -d ‘ ‘ -f 5)logVariables $LINENO aftersizeinfo "Shrunk $img from $beforesize to $aftersize"