wireguard-tools: replace backticks by $(...)

This replaces deprecated backticks by more versatile $(...) syntax.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

package/network/utils/wireguard-tools/files/wireguard_watchdog

@@ -27,7 +27,7 @@ check_peer_activity() {
   config_get public_key "${cfg}" "public_key"
   config_get endpoint_host "${cfg}" "endpoint_host"
   config_get endpoint_port "${cfg}" "endpoint_port"
-  persistent_keepalive=`wg show ${iface} persistent-keepalive | grep ${public_key} | awk '{print $2}'`
+  persistent_keepalive=$(wg show ${iface} persistent-keepalive | grep ${public_key} | awk '{print $2}')
 
   # only process peers with endpoints and keepalive set
   [ -z ${endpoint_host} ] && return 0;
@@ -42,16 +42,16 @@ check_peer_activity() {
   [ -n "${IPV4}" -o -n "${IPV6}" ] && return 0;
 
   # re-resolve endpoint hostname if not responding for too long
-  last_handshake=`wg show ${iface} latest-handshakes | grep ${public_key} | awk '{print $2}'`
+  last_handshake=$(wg show ${iface} latest-handshakes | grep ${public_key} | awk '{print $2}')
   [ -z ${last_handshake} ] && return 0;
-  idle_seconds=$((`date +%s`-${last_handshake}))
+  idle_seconds=$(($(date +%s)-${last_handshake}))
   [ ${idle_seconds} -lt 150 ] && return 0;
   logger -t "wireguard_monitor" "${iface} endpoint ${endpoint_host}:${endpoint_port} is not responding for ${idle_seconds} seconds, trying to re-resolve hostname"
   wg set ${iface} peer ${public_key} endpoint "${endpoint_host}:${endpoint_port}"
 }
 
 # query ubus for all active wireguard interfaces
-wg_ifaces=`ubus -S call network.interface dump | jsonfilter -e '@.interface[@.up=true]' | jsonfilter -a -e '@[@.proto="wireguard"].interface' | tr "\n" " "`
+wg_ifaces=$(ubus -S call network.interface dump | jsonfilter -e '@.interface[@.up=true]' | jsonfilter -a -e '@[@.proto="wireguard"].interface' | tr "\n" " ")
 
 # check every peer in every active wireguard interface
 config_load network