add bash script for checking kernel modules

content/rke/latest/en/os/_index.md

@@ -44,6 +44,15 @@ RKE runs on almost any Linux OS with Docker installed. Most of the development a
    * `modprobe module_name`
    * `lsmod | grep module_name`
    * `grep module_name /lib/modules/$(uname -r)/modules.builtin`, if it's a built-in module
+   * bash script
+     ```bash
+     for module in br_netfilter ip6_udp_tunnel ip_set ip_set_hash_ip ip_set_hash_net iptable_filter iptable_nat iptable_mangle iptable_raw nf_conntrack_netlink nf_conntrack nf_conntrack_ipv4   nf_defrag_ipv4 nf_nat nf_nat_ipv4 nf_nat_masquerade_ipv4 nfnetlink udp_tunnel veth vxlan x_tables xt_addrtype xt_conntrack xt_comment xt_mark xt_multiport xt_nat xt_recent xt_set  xt_statistic xt_tcpudp;
+     do
+       if ! lsmod | grep -q $module; then
+         echo "module $module is not present"
+       fi
+     done;     
+     ```
 
 Module name |
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