From cad2e0e11a9321cec88534a5537fe3157f522f0b Mon Sep 17 00:00:00 2001
From: rbaumbach <github@ryan.codes>
Date: Sat, 9 Jul 2016 20:45:54 -0700
Subject: [PATCH] Add getops to script to provide user the ability to skip
 autoexpanding process of the script

---
 README.md   |  6 +++---
 pishrink.sh | 49 +++++++++++++++++++++++++++++++++----------------
 2 files changed, 36 insertions(+), 19 deletions(-)

diff --git a/README.md b/README.md
index c9ac539..1286604 100644
--- a/README.md
+++ b/README.md
@@ -1,13 +1,13 @@
 # PiShrink #
 PiShrink is a bash script that automatically shrink a pi image that will then resize to the max size of the SD card on boot. This will make putting the image back onto the SD card faster and the shrunk images will compress better.
 
-`Usage: ./pishrink imagefile.img [newimagefile.img]`
+`Usage: ./pishrink [-s] imagefile.img [newimagefile.img]`
 
-If you specify the `newimagefile.img` parameter, the script will make a copy of `imagefile.img` and work off that. You will need enough space to make a full copy of the image to use that option.
+If the `-s` option is given the script will skip the autoexpanding part of the process.  If you specify the `newimagefile.img` parameter, the script will make a copy of `imagefile.img` and work off that. You will need enough space to make a full copy of the image to use that option.
 
 ## Example ##
 ```bash
-[user@localhost PiShrink]$ sudo ./shrink.sh pi.img 
+[user@localhost PiShrink]$ sudo ./shrink.sh pi.img
 e2fsck 1.42.9 (28-Dec-2013)
 Pass 1: Checking inodes, blocks, and sizes
 Pass 2: Checking directory structure
diff --git a/pishrink.sh b/pishrink.sh
index 0e49724..308b9fa 100755
--- a/pishrink.sh
+++ b/pishrink.sh
@@ -1,11 +1,23 @@
 #!/bin/bash
+
+usage() { echo "Usage: $0 [-s] imagefile.img [newimagefile.img]"; exit -1; }
+
+should_skip_autoexpand=false
+
+while getopts ":s" opt; do
+    case "${opt}" in
+        s) should_skip_autoexpand=true ;;
+        *) usage ;;
+    esac
+done
+shift $((OPTIND-1))
+
 #Args
 img=$1
 
 #Usage checks
 if [[ -z $img ]]; then
-  echo "Usage: $0 imagefile.img [newimagefile.img]"
-  exit -1
+  usage
 fi
 if [[ ! -e $img ]]; then
   echo "ERROR: $img is not a file..."
@@ -42,22 +54,27 @@ 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'`
 
-#Make pi expand rootfs on next boot
-mountdir=`mktemp -d`
-mount $loopback $mountdir
+#Check if we should make pi expand rootfs on next boot
+if [ "$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` != "a27a4d8192ea6ba713d2ddd15a55b1df" ]; then
-echo Creating new /etc/rc.local
-mv $mountdir/etc/rc.local $mountdir/etc/rc.local.bak
-cat <<\EOF > $mountdir/etc/rc.local
-#!/bin/bash
-/usr/bin/raspi-config --expand-rootfs
-rm -f /etc/rc.local; cp -f /etc/rc.local.bak /etc/rc.local; reboot
-exit 0
+  if [ `md5sum $mountdir/etc/rc.local | cut -d ' ' -f 1` != "a27a4d8192ea6ba713d2ddd15a55b1df" ]; then
+    echo Creating new /etc/rc.local
+    mv $mountdir/etc/rc.local $mountdir/etc/rc.local.bak
+    cat <<\EOF > $mountdir/etc/rc.local
+    #!/bin/bash
+    /usr/bin/raspi-config --expand-rootfs
+    rm -f /etc/rc.local; cp -f /etc/rc.local.bak /etc/rc.local; reboot
+    exit 0
 EOF
-chmod +x $mountdir/etc/rc.local
+    chmod +x $mountdir/etc/rc.local
+  fi
+  umount $mountdir
+else
+  echo Skipping autoexpanding process...
 fi
-umount $mountdir
 
 #Make sure filesystem is ok
 e2fsck -f $loopback
@@ -100,4 +117,4 @@ endresult=`parted -m $img unit B print free | tail -1 | cut -d ':' -f 2 | tr -d
 truncate -s $endresult $img
 aftersize=`ls -lah $img | cut -d ' ' -f 5`
 
-echo "Shrunk $img from $beforesize to $aftersize"
\ No newline at end of file
+echo "Shrunk $img from $beforesize to $aftersize"