tools/hv: reduce resouce usage in hv_get_dns_info helper

Remove the usage of cat. Replace the shell process with awk with 'exec'.
Also use a generic shell because no bash specific features will be used.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Wei Liu <wei.liu@kernel.org>
Link: https://lore.kernel.org/r/20241202120432.21115-1-olaf@aepfle.de
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20241202120432.21115-1-olaf@aepfle.de>

Author: olafhering

tools/hv/hv_get_dns_info.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 
 # This example script parses /etc/resolv.conf to retrive DNS information.
 # In the interest of keeping the KVP daemon code free of distro specific
@@ -10,4 +10,4 @@
 # this script can be based on the Network Manager APIs for retrieving DNS
 # entries.
 
-cat /etc/resolv.conf 2>/dev/null | awk '/^nameserver/ { print $2 }'
+exec awk '/^nameserver/ { print $2 }' /etc/resolv.conf 2>/dev/null