set-dns

#!/bin/sh

SET="0"
SERVERS=""
CONFFILE="/etc/defaults/set-dns.conf"

while getopts ":c:" cmd; do
    case $cmd in
        c)  CONFFILE="$OPTARG" ;;
    esac
done

[ -f "$CONFFILE" ] && . "$CONFFILE"

usage() {
    cat <<-EOT
Usage: `basename $0` [OPTION]... [SERVER]...
Show or set the DNS servers for the PrimaryService using scutil(1).

  -c <file>  use <file> as the config file, instead of
               /etc/defaults/set-dns.conf
  -s         set server list
  -?         display this help and exit

By default, SERVERS is set to:

    $SERVERS
    
To change this, edit the set-dns.conf file.
EOT
}

OPTIND=1
while getopts ":c:s?" cmd; do
    ## echo "$cmd/$OPTIND: $OPTARG"
    case $cmd in
        c)  ;;
        s)  SET="1" ;;
        [?]) usage; exit ;;
    esac
done
shift $((OPTIND - 1))

if [ "$*" != "" ]; then
    SERVERS="$*"
fi

SERVICE=`echo "show State:/Network/Global/IPv4" | scutil | awk '/PrimaryService/ { print $3 }'`
KEY="State:/Network/Service/$SERVICE/DNS"

if [ "$SET" = "1" ]; then
    if [ "`id -u`" != "0" ]; then
        echo "You must be root to set DNS servers."
        exit
    fi

    scutil <<-EOT
        open
        get $KEY
        d.add ServerAddresses * $SERVERS
        d.show
        set $KEY
        close
EOT
else
    scutil <<-EOT
        open
        show $KEY
        close
EOT
fi