diff --git a/pishrink.sh b/pishrink.sh
index 1d68900..1294aad 100755
--- a/pishrink.sh
+++ b/pishrink.sh
@@ -1,24 +1,69 @@
 #!/bin/bash
 
-function cleanup() {
-  if losetup $loopback &>/dev/null; then
-	losetup -d "$loopback"
-  fi
+version="v0.1"
+
+function info() {
+	echo "$1..."
 }
 
-usage() { echo "Usage: $0 [-s] imagefile.img [newimagefile.img]"; exit -1; }
+function error() {
+	echo -n "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
+}
+
+usage() { echo "Usage: $0 [-sd] imagefile.img [newimagefile.img]"; exit -1; }
 
 should_skip_autoexpand=false
+debug=false
 
-while getopts ":s" opt; do
+while getopts ":sd" opt; do
   case "${opt}" in
     s) should_skip_autoexpand=true ;;
+    d) debug=true;;
     *) usage ;;
   esac
 done
 shift $((OPTIND-1))
 
+CURRENT_DIR=$(pwd)
+SCRIPTNAME="${0##*/}"
+LOGFILE=${CURRENT_DIR}/${SCRIPTNAME%.*}.log
+
+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
@@ -26,11 +71,11 @@ if [[ -z "$img" ]]; then
   usage
 fi
 if [[ ! -f "$img" ]]; then
-  echo "ERROR: $img is not a file..."
+  error $LINENO "$img is not a file..."
   exit -2
 fi
 if (( EUID != 0 )); then
-  echo "ERROR: You need to be running as root."
+  error $LINENO "You need to be running as root."
   exit -3
 fi
 
@@ -38,17 +83,17 @@ fi
 for command in parted losetup tune2fs md5sum e2fsck resize2fs; do
   which $command 2>&1 >/dev/null
   if (( $? != 0 )); then
-    echo "ERROR: $command is not installed."
+    error $LINENO "$command is not installed."
     exit -4
   fi
 done
 
 #Copy to new file if requested
 if [ -n "$2" ]; then
-  echo "Copying $1 to $2..."
+  info "Copying $1 to $2..."
   cp --reflink=auto --sparse=always "$1" "$2"
   if (( $? != 0 )); then
-    echo "ERROR: Could not copy file..."
+    error $LINENO "Could not copy file..."
     exit -5
   fi
   old_owner=$(stat -c %u:%g "$1")
@@ -60,15 +105,36 @@ fi
 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)
+logVariables $LINENO beforesize
+if ! parted_output=$(parted -ms "$img" unit B print); then
+	rc=$?
+	error $LINENO "parted failed with rc $rc"
+	exit -6
+fi
+parted_output=$(tail -n 1 <<< $parted_output)
+logVariables $LINENO parted_output
+
 partnum=$(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")
+logVariables $LINENO partnum partstart
+
+info "Mounting image"
+if ! loopback=$(losetup -f --show -o $partstart "$img"); then
+	rc=$?
+	error $LINENO "losetup failed with rc $rc"
+	exit -7
+fi
+if ! tune2fs_output=$(tune2fs -l "$loopback"); then
+	error $LINENO "tunefs failed"
+	exit -8
+fi
 currentsize=$(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
@@ -146,43 +212,81 @@ else
 fi
 
 #Make sure filesystem is ok
-e2fsck -p -f "$loopback"
-minsize=$(resize2fs -P "$loopback" | cut -d ':' -f 2 | tr -d ' ')
+info "Checking filesystem"
+if ! e2fsck -p -f "$loopback"; then
+	rc=$?
+	error $LINENO "fsck failed with rc $rc"
+	exit -9
+fi
+
+if ! minsize=$(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
-  echo "ERROR: Image already shrunk to smallest size"
-  exit -6
+  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
-  echo "ERROR: resize2fs failed..."
+  error $LINENO "resize2fs failed"
   mount "$loopback" "$mountdir"
   mv "$mountdir/etc/rc.local.bak" "$mountdir/etc/rc.local"
   umount "$mountdir"
   losetup -d "$loopback"
-  exit -7
+  exit -12
 fi
 sleep 1
 
 #Shrink partition
 partnewsize=$(($minsize * $blocksize))
 newpartend=$(($partstart + $partnewsize))
-parted -s -a minimal "$img" rm $partnum >/dev/null
-parted -s "$img" unit B mkpart primary $partstart $newpartend >/dev/null
+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
-endresult=$(parted -ms "$img" unit B print free | tail -1 | cut -d ':' -f 2 | tr -d 'B')
-truncate -s $endresult "$img"
-aftersize=$(ls -lh "$img" | cut -d ' ' -f 5)
+info "Shrinking image"
+if ! endresult=$(parted -ms "$img" unit B print free); then
+	rc=$?
+	error $LINENO "parted failed with rc $rc"
+	exit -15
+fi
 
-echo "Shrunk $img from $beforesize to $aftersize"
+endresult=$(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 $rc"
+	exit -16
+
+aftersize=$(ls -lh "$img" | cut -d ' ' -f 5)
+logVariables $LINENO aftersize
+
+info "Shrunk $img from $beforesize to $aftersize"