getting ip & set default routing

#!/bin/bash
print_help () {
    echo "use setroute <interface> [svt] [table]";
    echo "<interface> pptp tunnel interface (e.g. ppp0)";
    echo "Options:";
    echo "v - set VIA parameter";
    echo "s - set SRC parameter";
    echo "t - set routing table";
    echo "[table] - routing table (in /etc/iproute2/rt_tables)";
    echo "if the table is not specified, used default route table";
}

SETVIA=0
SETSRC=0
ROUTINGTABLE=""

#Proveryaem parametry
if [ -z "$1" ]; then #esli 1 opcii net
    print_help #pechataem help i uhodim
    exit 2
fi

if [ "$1" = "-h" ] ;then #esli v 1 opcii zapros pomoshi
    print_help #pechataem help i uhodim
    exit 2
fi

if [ "$1" = "--help" ] ;then #esli v 1 opcii zapros pomoshi
    print_help #pechataem help i uhodim
    exit 2
fi


if  echo "$2"| grep -q "v"; then #ustanavlivat li VIA
    SETVIA=1
fi

if  echo "$2"| grep -q "s"; then #ustanavlivat li SRC
    SETSRC=1
fi

if  echo "$2"| grep -q "t"; then #ustanavlivat li tablicu
    if [ -n $3 ]; then #esli ustanavlivat' proveraem 3 parametr
    if grep -wq "$3" "/etc/iproute2/rt_tables"; then #est' li tablica
        ROUTINGTABLE=$3
    else
        echo "Error! Table $3 not found in rt_tables"
        exit 1
    fi
    fi
fi


#Proveryaem, podnyat li interfeis
ifconfig $1>/dev/null
if [ "$?" -ne 0 ]; then
    echo "Interface $1 error ";
    exit 1
fi

#Izvlekaem IP
TMPGREP=`ifconfig $1|grep "destination"`;#Grep'aem 'destination' (na toi zhe strochke i 'inet')
if [ -z "$TMPGREP" ]; then
    echo "Error! IP data not found!"
    exit 1
fi

SRC=`echo $TMPGREP|awk ' {print $2} '`   # S pomoshju awk izvlekaem nujnie
VIA=`echo $TMPGREP|awk ' {print $6} '`   # stolbcy s ip (razdelitel probel)


# Vivodim summary i formiruem elementy commandy
echo "Device: $1 OK"
if [ $SETSRC -eq 1 ]; then
    echo "SRC set. IP: $SRC"
    SRC="src "$SRC
else
    echo "SRC not set"
    SRC=""
fi

if [ $SETVIA -eq 1 ]; then
    echo "VIA set. IP: $VIA"
    VIA="via "$VIA
else
    echo "VIA not set"
    VIA=""
fi

if [ -z $ROUTINGTABLE ]; then
    echo "Use default routing table."
else
    echo "Routing table: "$ROUTINGTABLE
    ROUTINGTABLE="table "$ROUTINGTABLE
fi

#ustanavlivaem routing
ip route del default $ROUTINGTABLE
ip route add default dev $1 $VIA $SRC $ROUTINGTABLE
if [ $? -eq 0  ]; then
    echo "Routing set!"
else
    echo "Error detected!"
fi