This script is used to connect to wify

connect_wify.sh

#!/bin/bash
# This script is writen by billy3321
# this script is used to connect to wireless network.
#set -o xtrace

IF=$(echo $1 | tr 'A-Z' 'a-z')
AUTH=$(echo $2 | tr 'A-Z' 'a-z')
ESSID=$3
KEY=$4


function help(){
    #This is print function, use to print help.
    echo "usage:"
    echo '    connect_wify.sh -h : print this help'
    echo '    connect_wify.sh $IF $AUTH $ESSID $KEY'
    echo '    $AUTH shoud be in none|wep|wpa|wpa2'
    echo "example:"
    echo "    connect_wify.sh wlan0 wpa dlink 1234567890"
}

function initif(){
    #Init the interface
    sudo ifconfig $IF down
    sudo iwconfig $IF mode managed
    sudo ifconfig $IF up
    sleep 1
    #Try to scan the essid for test the wireless card
    sudo iwlist $IF scan
    if [ $? -ne 0 ]; then
        echo "the wireless card cannot work."
        exit
    fi
    sleep 1
}

if  [ -z $IF ] || [ $IF = "help" ] || [ $IF = "-h" ] || [ $IF = "--help" ]; then
    help
    exit
else
    read -p "press ENTER to continue, Ctrl-C to exit." INPUT
fi

case "$AUTH" in
    "none")
    #The essid don't use key
    initif
    sudo iwconfig $IF essid $ESSID
    ;;
    "wep")
    #The essid use wep key.
    initif
    #hex key
    sudo iwconfig $IF essid $ESSID key $KEY
    #ascii key
    #sudo iwconfig $IF essid $ESSID key s:${KEY}
    ;;
    "wpa")
    initif
    #First way to connect
    sudo iwconfig $IF essid $ESSID
    sudo iwpriv $IF set AuthMode=WPAPSK
    sudo iwpriv $IF set EncrypType=TKIP
    sudo iwpriv $IF set WPAPSK=$KEY
    #Second way to connect
    #wpa_passphrase $ESSID $KEY > /tmp/wpa.conf
    #sudo wpa_supplicant -BDwext -iwlan0 -c/tmp/wpa.conf
    ;;
    "wpa2")
    initif
    #First way to connect
    sudo iwconfig $IF essid $ESSID
    sudo iwpriv $IF set AuthMode=WPA2PSK
    sudo iwpriv $IF set EncrypType=TKIP
    sudo iwpriv $IF set WPA2PSK=$KEY
    #Second way to connect
    #wpa_passphrase $ESSID $KEY > /tmp/wpa.conf
    #sudo wpa_supplicant -BDwext -iwlan0 -c/tmp/wpa.conf
    ;;
    *)
    echo "auth mode should in none, wep, wpa, wpa2"
    help
    ;;
esac

#Get the ip through dhcp
sleep 1
sudo dhclient -v $IF