flush dns cache for different versions of OSX.

osx-flush-dns.sh

#! /bin/sh
# super-simplified version of flushDNSCache from Tunnelblick

osx_version=$(/usr/bin/sw_vers | awk '/ProductVersion:/ {print $2}')
echo "OSX: ${osx_version}"

case "${osx_version}" in
  10.9.*|10.11.*)
    sudo /usr/bin/dscacheutil -flushcache
    sudo /usr/bin/pkill -HUP mDNSResponder
    ;;
  10.[78].*)
    sudo /usr/bin/pkill -HUP mDNSResponder
    ;;
  10.[56].*)
    sudo dscacheutil -flushcache
    ;;
  10.10.*)
    sudo discoveryutil udnsflushcaches
    ;;
  *)
    echo "don't know how. sorries..."
    exit
esac

echo "flushed..."