patch_strings_in_file

patch_strings_in_file.sh

function patch_strings_in_file() {
    local FILE="$1"
    local PATTERN="$2"
    local REPLACEMENT="$3"

    # Find all unique strings in FILE that contain the pattern
    HASSTRING=$(grep ${PATTERN} ${FILE})

    if [ "${HASSTRING}" != "" ] ; then
        echo "File '${FILE}' contain strings with '${PATTERN}' in them:"

        OLD_STRING=${PATTERN}
        NEW_STRING=${REPLACEMENT}

        # Create null terminated ASCII HEX representations of the strings
        OLD_STRING_HEX="$(echo -n ${OLD_STRING} | xxd -g 0 -u -ps -c 256)00"
        NEW_STRING_HEX="$(echo -n ${NEW_STRING} | xxd -g 0 -u -ps -c 256)00"

        if [ ${#NEW_STRING_HEX} -le ${#OLD_STRING_HEX} ] ; then
          # Pad the replacement string with null terminations so the
          # length matches the original string
          while [ ${#NEW_STRING_HEX} -lt ${#OLD_STRING_HEX} ] ; do
            NEW_STRING_HEX="${NEW_STRING_HEX}00"
          done

          # Now, replace every occurrence of OLD_STRING with NEW_STRING
          echo -n "Replacing ${OLD_STRING} with ${NEW_STRING}... "
          tempfile="/tmp/.tmp"
          hexdump -ve '1/1 "%.2X"' ${FILE} | \
          sed "s/${OLD_STRING_HEX}/${NEW_STRING_HEX}/g" | \
          xxd -r -p > $tempfile
          chmod --reference ${FILE} $tempfile
          sudo mv $tempfile ${FILE}
          echo "Done!"
        else
          echo "New string '${NEW_STRING}' is longer than old" \
               "string '${OLD_STRING}'. Skipping."
        fi
    else
      echo "${PATTERN} not found in ${FILE}!"
    fi
}