diff --git a/bash/ucftar_pack b/bash/ucftar_pack
index 4852d19..6ec66d8 100755
--- a/bash/ucftar_pack
+++ b/bash/ucftar_pack
@@ -1,11 +1,14 @@
 #!/bin/bash
 display_help() {
-    (>&2 echo "Usage: $(basename "$0") [-hv] [-f outfile] filename")
+    (>&2 echo "Usage: $(basename "$0") [-chqv] [-o outfile] indir iseq")
     (>&2 echo "UCF tar packer")
     (>&2 echo)
-    (>&2 echo "   filename                path to arbitrary file with correct sequence number")
-    (>&2 echo "   -f, --file              output file (default: snapshot_XXXX.ucf.tar)")
+    (>&2 echo "   indir                   path to input directory")
+    (>&2 echo "   iseq                    sequence number")
+    (>&2 echo "   -c, --checksum          compares checksums after the archive is created")
     (>&2 echo "   -h, --help              display this help message")
+    (>&2 echo "   -o, --outfile           output file (default: snapshot_XXXX.ucf.tar)")
+    (>&2 echo "   -q, --quicksum          same as --checksum, but compares only first bytes")
     (>&2 echo "   -v, --verbose           verbose output")
 }
 exit_script() {
@@ -21,6 +24,8 @@ if [ $# -eq 0 ]; then
 fi
 fout=""
 verbose=0
+checksum=0
+quicksum=0
 POSITIONAL=()
 while [[ $# -gt 0 ]]
 do
@@ -31,7 +36,7 @@ case $key in
     exit 0
     shift # past argument
     ;;
-    -f|--file)
+    -o|--outfile)
     fout="$2"
     shift # past argument
     shift # past value
@@ -40,6 +45,14 @@ case $key in
     verbose=1
     shift # past argument
     ;;
+    -c|--checksum)
+    checksum=1
+    shift # past argument
+    ;;
+    -q|--quicksum)
+    quicksum=1
+    shift # past argument
+    ;;
     *)    # unknown option
     POSITIONAL+=("$1") # save it in an array for later
     shift # past argument
@@ -49,13 +62,8 @@ done
 set -- "${POSITIONAL[@]}"
 
 # Parse input filename
-din=$(dirname $1)
-fin=$(basename $1)
-seqnum=$(echo $fin | grep -o '_[0-9]\+')
-if [ -z "$seqnum" ]; then
-  (>&2 echo "[Error] No sequence number found in input filename.")
-  exit 1;
-fi
+din=$1
+seqnum=$(printf %04d $2) 
 
 # Construct output filename if not specified
 if [ -z "$fout" ]; then
@@ -68,12 +76,12 @@ if [ $verbose -eq 1 ]; then
 fi
 
 # Check input files
-fparam="parameters${seqnum}.asc"
-fgrid="grid${seqnum}.bin"
-fproc="proc${seqnum}.bin"
-fpart="particles${seqnum}.bin"
-fbuvwp="uvwp"
-fbscal="scal"
+fparam="parameters_${seqnum}.asc"
+fgrid="grid_${seqnum}.bin"
+fproc="proc_${seqnum}.bin"
+fpart="particles_${seqnum}.bin"
+fbuvwp="uvwp_"
+fbscal="scal_"
 
 # Check if obligatory files are present
 if [ ! -s ${din}/${fparam} ]; then
@@ -101,7 +109,7 @@ fi
 
 fuvwp=()
 for (( ii=0; ii<$nproc; ii++ )); do
-  ftmp=$(printf uvwp${seqnum}.%05d $ii)
+  ftmp=$(printf ${fbuvwp}${seqnum}.%05d $ii)
   if [ ! -s ${din}/${ftmp} ]; then
     (>&2 echo "[Error] File not found or empty: ${din}/${ftmp}")
     exit 1
@@ -113,7 +121,7 @@ done
 if grep -q "scalar" "${din}/${fparam}"; then
   fscal=()
   for (( ii=0; ii<$nproc; ii++ )); do
-    ftmp=$(printf scal${seqnum}.%05d $ii)
+    ftmp=$(printf ${fbscal}${seqnum}.%05d $ii)
     if [ ! -s ${din}/${ftmp} ]; then
       (>&2 echo "[Error] File not found or empty: ${din}/${ftmp}")
       exit 1
@@ -136,16 +144,50 @@ if [ $verbose -eq 1 ]; then
   fi
 fi
 
+# Create a full file list for the archive
+flist=(${fparam} ${fgrid} ${fproc} ${fpart} ${fuvwp[@]} ${fscal[@]})
+
 # Now tar them and remove seqence number from file names while doing so
+flagtar=""
 if [ $verbose -eq 1 ]; then
-  flagtar="-v"
+  flagtar="$flagtar --verbose"
 fi
 trap exit_script SIGINT SIGTERM
-tar $flagtar --format ustar --transform="flags=r;s|$seqnum||" --directory=${din} -cf ${fout} ${fparam} ${fgrid} ${fproc} ${fpart} ${fuvwp[@]} ${fscal[@]}
+tar $flagtar --format ustar --transform="flags=r;s|_$seqnum||" --directory=${din} -cf ${fout} ${flist[@]}
 tarexit=$?
 # Set exit status accoring to tar
 if [ $tarexit -ne 0 ]; then
   (>&2 echo "tar failed with exit code $tarexit")
   exit 254
 fi
+
+# Compare checksums (CNC32), if flag is set
+#din="./archive/" #for testing
+flistx=($(echo ${flist[@]} | sed s/"_$seqnum"/""/g))
+if [ $checksum -eq 1 ]; then
+  for ii in "${!flistx[@]}"; do 
+    if [ $verbose -eq 1 ]; then
+      (>&2 echo "Verifying checksum: ${flist[$ii]}")
+    fi
+    crcori=$(cksum ${din}/${flist[$ii]} | awk '{ print $1, $2 }')
+    crctar=$(tar --to-command='cksum -' -xf ${fout} ${flistx[$ii]} | awk '{ print $1, $2 }')
+    if [ "$crcori" != "$crctar" ]; then
+      (>&2 echo "Verification failed: ${flist[$ii]} ${flistx[$ii]}")
+      exit 5
+    fi
+  done
+elif [ $quicksum -eq 1 ]; then
+  for ii in "${!flistx[@]}"; do
+    if [ $verbose -eq 1 ]; then
+      (>&2 echo "Verifying partial checksum: ${flist[$ii]}")
+    fi
+    crcori=$(head -c 1M ${din}/${flist[$ii]} | cksum -)
+    crctar=$(tar --to-command='head -c 1M' -xf ${fout} ${flistx[$ii]} | cksum -)
+    if [ "$crcori" != "$crctar" ]; then
+      (>&2 echo "Verification failed: ${flist[$ii]} ${flistx[$ii]}")
+      exit 5
+    fi
+  done
+fi
+
 exit 0