How to get the output of execute shell script in lua api - bash

Question

I am newbie in luci and lua api. Now I have problem about remove firewall rule from luci webgui in opnewrt. I know delete the rule is using the uci command : uci delete firewall.#rule[index]
But I don't know the index exectly. So I use blow shell script name index.sh to find the index by key word.
uci show firewall | grep $1 | grep -oE '\[.*?\]' | sed 's/[][]//g' | head -n 1
Here $1 is the mac address.
My process is get the mac address from luci web and remove the firewall rule of block the
network access from the mac address I set before. To recover the network access of the mac address.
But I use the lua api of luci.sys.exec and luci.util.exec to get the output of firewall rule index that are all wrong.
My example code:
1.Get the mac address from luci
local del_mac = protocol.urldecode(luci.http.formvalue("deleteMac"))
2.Execute the the shell script to get the index
local ruleindex = ut.trim(tostring(luci.sys.exec("index.sh '" .. del_mac .."'"))
local uci_delete_rule = "uci delete firewall.#rule['" .. ruleindex .. "]'"
luci.sys.exec(uci_delete_rule)
or
local index = "index.sh %s" %{list_del_mac}
local rule_index = ut.trim(tostring(luci.util.exe(index)))
local uci_delete_rule = "uci delete firewall.#rule['" .. rule_index .. "]'"
luci.sys.exec(uci_delete_rule)
3.Reload the firewall rule
luci.sys.exec("uci commit firewall")
luci.sys.exec("fw3 reload")
Can anyone help me to reslove the problem?
Thank you for your help

Answer 1

This doesn't look right to me: "index.sh %s" %{list_del_mac} Unless it's short for string.format in luci, that's not proper Lua. Concatenate your command string, or actually use string.format
"index.sh " ..list_del_mac
or
string.format( "index.sh %s", list_del_mac )
also, to get the return value after execution, you need to send it to a variable
return_value = luci.sys.exec(uci_delete_rule)
print( return_value )