ERROR:  ./client-disconnect.sh: 22: ./client-disconnect.sh: arithmetic expression: expecting primary:  + I just need to know how to fix it.  It's for user accounting with OpenVPN.Script#!/bin/sh# Copyright Josh Cepek# This file is part of the openvpn-dynamic project, available from:# https://github.com/QueuingKoala/openvpn-dynamic# Dual-licensed under GPLv3 and BSD-3-clause# BEGIN User Disconnect Accountinglog_file=/var/log/openvpn-disconnect.log# Be platform friendly to both GNU and BSD-userland:if date --help >/dev/null 2>&1; then    get_date() { date -d @$1 +'%F-%H:%M'; }else    get_date() { date -r $1 +'%F-%H:%M'; }fi# Vars used in log line:#time:date_from=$(get_date $time_unix)unix_to=$(($time_unix + $time_duration))date_to=$(get_date $unix_to)time_h=$(($time_duration / 3600))time_m=$(( $time_duration % 3600 / 60 ))#bw:bw_up=$(( $bytes_received / 1000**2 ))\.$(( $bytes_received % 1000**2 / 1000 ))bw_down=$(( $bytes_sent / 1000**2 ))\.$(( $bytes_sent % 1000**2 / 1000 ))# Format the line for export:line=User '$common_name' \using $ifconfig_pool_remote_ip \from $trusted_ip:$trusted_port \for $date_from to $date_to ($time_h:$time_m) \BW(up/down) $bw_up/$bw_down# Append it to the logecho $line >> $log_file# END User Disconnect Accountingexit 0
/bin/sh script error arithmetic expression: expecting primary:  +  
linux;shell script;scripting;openvpn;posix