remove_ctf_datetime

#!/bin/bash
#
# Copyright (C) 2018, Robert Oostenveld
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA


displayhelp() { 
echo 
echo This utility removes the date and time of acquisition from a CTF dataset.
echo
echo You should also use newDs with the -anon option to remove subject identifiers.
echo
echo Use as
echo $0 [-d] [-t] '<DATASET>'
echo
echo Optional arguments are
echo   -d      remove the date from the res4 file
echo   -t      remove the time from the res4 file
echo 
}

echoerr() {
echo "$@" 1>&2;
}

function replaceByte() {
# See https://stackoverflow.com/questions/4783657/cli-write-byte-at-address-hexedit-modify-binary-from-the-command-line
# param 1: file
# param 2: offset
# param 3: value
    printf "$(printf '\\x%02X' $3)" | dd of="$1" bs=1 seek=$2 count=1 conv=notrunc &> /dev/null
}

##############################################################################
# parse command line arguments
##############################################################################

REMOVEDATE=0
REMOVETIME=0

POSITIONAL=()
while [[ $# -gt 0 ]]
do
key="$1"
case $key in
    -h|--help)
    displayhelp
    exit 0
    ;;
    -d|--date)
    REMOVEDATE=1
    shift # past argument
    ;;
    -t|--time)
    REMOVETIME=1
    shift # past argument
    ;;
    *)    # unknown option
    POSITIONAL+=("$1") # save it in an array for later
    shift # past argument
    ;;
esac
done
set -- "${POSITIONAL[@]}" # restore positional parameters

DATASET=$(realpath "$1")

##############################################################################
# test the options
##############################################################################

if [ -z ${DATASET} ]; then
echoerr ERROR: dataset directory must be specified
exit 1
fi

if [ $REMOVEDATE = 0 -a $REMOVETIME = 0 ] ; then
echoerr ERROR: either date and/or time should be specified to be removed
exit 1
fi

##############################################################################
# do the work
##############################################################################

if [ $REMOVETIME = 1 ] ; then 
echo removing time from ${DATASET}
OFFSET=778
# please note that the command continues far to the right
printf "00:00                                                                                                                                                                                                                                                          " | dd of=${DATASET} bs=1 seek=$OFFSET count=255 conv=notrunc &> /dev/null
fi

if [ $REMOVEDATE = 1 ] ; then 
echo removing date from ${DATASET}
OFFSET=1033
# please note that the command continues far to the right
printf "01-Jan-1970                                                                                                                                                                                                                                                    " | dd of=${DATASET} bs=1 seek=$OFFSET count=255 conv=notrunc &> /dev/null 
fi