NFTTables or IPTables switcher Ubuntu & Debian

NFTTables_or_IPTables_switcher_Ubuntu_and_Debian.sh

#!/bin/bash
which_tables=$1
timeout_time=180

function set_iptables() {
          arg=$1
          table=$2
          find -L /usr/sbin -name 'iptables*' -type l -exec rm -rf {} \;
          find -L /usr/sbin -name 'ip6tables*' -type l -exec rm -rf {} \;
          echo 0 | update-alternatives $arg iptables /usr/sbin/iptables-$table
          echo 0 | update-alternatives $arg iptables-save /usr/sbin/iptables-$table-save
          echo 0 | update-alternatives $arg iptables-restore /usr/sbin/iptables-$table-restore
          
          echo 0 | update-alternatives $arg ip6tables /usr/sbin/ip6tables-$table
          echo 0 | update-alternatives $arg ip6tables-save /usr/sbin/ip6tables-$table-save
          echo 0 | update-alternatives $arg ip6tables-restore /usr/sbin/ip6tables-$table-restore
          
          echo 0 | update-alternatives $arg arptables /usr/sbin/arptables-$table
          echo 0 | update-alternatives $arg ebtables /usr/sbin/ebtables-$table
          if [[ "$arg" == '--set' ]]; then
                    echo 0 | update-alternatives --install /usr/sbin/arptables arptables /usr/sbin/arptables-$table 20 --slave /usr/sbin/arptables-save arptables-save /usr/sbin/arptable-$table-save --slave /usr/sbin/arptables-restore arptables-restore /usr/sbin/arptables-$table-restore
                    echo 0 | update-alternatives \
                              --install /usr/sbin/iptables iptables /usr/sbin/iptables-$table 10 \
                              --slave /usr/sbin/iptables-restore iptables-restore /usr/sbin/iptables-$table-restore \
                              --slave /usr/sbin/iptables-save iptables-save /usr/sbin/iptables-$table-save
           fi
           echo 0 | update-alternatives --display iptables
           echo 0 | update-alternatives --display ip6tables
           echo 0 | update-alternatives --display arptables
           echo 0 | update-alternatives --display ebtables
}

is_nft_tables_iptables=$(iptables -V | grep -o nf_tables)

case "$which_tables" in
      purge-nftables | purge-nftable | purge-firewalld | remove-nftables | remove-nftable | remove-firewalld | rm-nftables | rm-nftable | rm-firewalld )
           pkg_list=$(apt list --installed | grep "nft\|firewalld" | awk -F/ '{print $1}' | grep -v "libnftnl11")
           if [[ -n $pkg_list ]]; then
              timeout $timeout_time yes | timeout $timeout_time apt purge -y firewalld nftables python3-nftables
              printf '%s\n' $pkg_list | xargs timeout $timeout_time apt purge -y
           fi
      ;;
      firewalld | nftables | nftable )
      
        if ! command -v nft; then
           timeout $timeout_time yes | timeout $timeout_time apt install -y firewalld nftables
        fi
        
        if [[ -z $is_nft_tables_iptables ]]; then
           set_iptables --set nft
           update-alternatives --config iptables-nft
        fi
      ;;
      iptables-nft | iptables-nftables | nft )
         
         if ! command -v iptables-nft; then
              timeout $timeout_time yes | timeout $timeout_time apt install -y ipset iptables
         fi
         if [[ -n $is_nft_tables_iptables ]]; then
              set_iptables --remove legacy
              set_iptables --set nft
              update-alternatives --config iptables-nft
         fi
      ;;
      ip | iptables | ipt | ip-tables ) 
      
        if ! command -v iptables-legacy; then
             timeout $timeout_time yes | timeout $timeout_time apt install -y iptables ipset
             timeout $timeout_time yes | timeout $timeout_time apt install -y ip6tables
        fi
        if [[ -n $is_nft_tables_iptables ]]; then
             set_iptables --remove nft
             set_iptables --set legacy
             update-alternatives --config iptables
             
             find -L /sbin -name 'iptables*' -type l -exec rm -rf {} \;
             find -L /sbin -name 'ip6tables*' -type l -exec rm -rf {} \;
             
             ln -s /etc/alternatives/iptables /sbin/iptables
             ln -s /etc/alternatives/iptables-save /sbin/iptables-save
             ln -s /etc/alternatives/iptables-restore /sbin/iptables-restore
             ln -s /sbin/xtables-legacy-multi /sbin/ip6tables
             ln -s /sbin/xtables-legacy-multi /sbin/ip6tables-save
             ln -s /sbin/xtables-legacy-multi /sbin/ip6tables-restore
         fi
      ;;
esac 
systemctl restart firewalld.service