bash dialog script to configure network interface in linux based system.

netconfig.sh

#!/bin/bash
#The MIT License 
# 
#Permission is hereby granted, free of charge, to any person obtaining a copy 
#of this software and associated documentation files (the "Software"), to deal 
#in the Software without restriction, including without limitation the rights 
#to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
#copies of the Software, and to permit persons to whom the Software is 
#furnished to do so, subject to the following conditions: 
# 
#The above copyright notice and this permission notice shall be included in 
#all copies or substantial portions of the Software. 

list_interfaces()
{
    interfaces=$(ls /sys/class/net/)
}

get_if_address()
{
    echo $(ifconfig $1 | grep -o 'inet addr:[0-9]\+\.[0-9]\+\.[0-9]\+\.[0-9]\+' | grep -o [0-9].*)
}

get_if_netmask()
{
    echo $(ifconfig $1 | grep -o 'Mask:[0-9]\+\.[0-9]\+\.[0-9]\+\.[0-9]\+' | grep -o [0-9].*)
}

get_if_gateway()
{
    echo $(ip route show | grep -o 'default via [0-9]\+\.[0-9]\+\.[0-9]\+\.[0-9]\+' | grep -o [0-9].*)
}
get_if_hwaddress()
{
    echo $(ifconfig $1 | grep -o '[A-F0-9]\+\:[A-F0-9]\+\:[A-F0-9]\+\:[A-F0-9]\+\:[A-F0-9]\+\:[A-F0-9]')
}

select_interface()
{
    list_interfaces
    interfaceArray=()
        while read name; do
            interfaceArray+=($name "")
    done <<< "$interfaces"

    interface=$(dialog    --stdout \
                          --title "Network Interfaces" \
                          --backtitle "Linux managment network interface" \
                          --ok-label "Next" \
                          --no-cancel \
                          --menu "Select an interface:" \
                          20 30 30 \
                          "${interfaceArray[@]}")
   echo $interface
}

create_interface_file()
{
cat << EOF >  $1
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
auto lo
iface lo inet loopback
EOF
}

write_interface_file()
{ 
    if [ ! -f $1 ]; then
        create_interface_file $1
    fi
    echo "" >> $1
    echo "$2" >> $1
}

config_interface()
{   
    if="$1"
    address="$2"
    netmask="$3"
    gateway="$4"
    hwaddress="$5"


    exec 3>&1
    config=$(dialog --ok-label "Ok" \
            --backtitle "Linux managment network interface" \
            --title "Network interface $if config" \
            --form "Configure network interface" \
              15 50 0 \
            "address:"      1 1     "$address"      1 10 15 0 \
            "netmask:"      2 1	    "$netmask"      2 10 15 0 \
            "gateway:"      3 1	    "$gateway"      3 10 15 0 \
            "hwaddress:"    4 1     "$hwaddress"    4 11 17 0 \
            2>&1 1>&3 | 
            {
                read -r address
                read -r netmask
                read -r gateway
                read -r hwaddress   
                
                result=$(printf "auto $if \niface $if inet static\n\taddress $address\n\tnetmask $netmask\n\tgateway $gateway\n\thwaddress $hwaddress")                
                write_interface_file "interfaces" "$result"                  
            })
    exec 3>&-
} 

while : ; do

    if="$(select_interface)"
    config_interface "$if" "$(get_if_address $if)" "$(get_if_netmask $if)"  "$(get_if_gateway)" "$(get_if_hwaddress $if)"

    if (dialog  --title "Finish" \
                --backtitle "Linux managment network interface" \
                --yesno "Do you want configure another interface?" 10 60) then
        continue
    else
        break
    fi
    
done