List iptables rules as append command

It's super simple: iptables -S gives you exactly what you ask for.

You can get similar output by using iptables-save command:

*nat
:PREROUTING ACCEPT [381:53396]
:INPUT ACCEPT [286:22260]
:OUTPUT ACCEPT [1462:92025]
:POSTROUTING ACCEPT [1450:91003]
-A POSTROUTING -s 192.168.123.0/24 ! -d 192.168.123.0/24 -p tcp -j MASQUERADE --to-ports 1024-65535 
-A POSTROUTING -s 192.168.123.0/24 ! -d 192.168.123.0/24 -p udp -j MASQUERADE --to-ports 1024-65535 

There are numbers and some extra info, but you can remove them by writing something like that:

iptables-save | grep -v -e "^[*:#]" -e "COMMIT" | cat -n

And the output:

     1  -A POSTROUTING -s 192.168.123.0/24 ! -d 192.168.123.0/24 -p tcp -j MASQUERADE --to-ports 1024-65535 
     2  -A POSTROUTING -s 192.168.123.0/24 ! -d 192.168.123.0/24 -p udp -j MASQUERADE --to-ports 1024-65535