flush cache

flush-cache.sh

#!/usr/bin/env bash

# Copyright 2018 Bushbaby Multimedia
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
# DEALINGS IN THE SOFTWARE.

# see http://coolestguidesontheplanet.com/clear-the-local-dns-cache-in-osx/

vercomp () {
    if [[ $1 == $2 ]]
    then
        return 0
    fi
    local IFS=.
    local i ver1=($1) ver2=($2)
    # fill empty fields in ver1 with zeros
    for ((i=${#ver1[@]}; i<${#ver2[@]}; i++))
    do
        ver1[i]=0
    done
    for ((i=0; i<${#ver1[@]}; i++))
    do
        if [[ -z ${ver2[i]} ]]
        then
            # fill empty fields in ver2 with zeros
            ver2[i]=0
        fi
        if ((10#${ver1[i]} > 10#${ver2[i]}))
        then
            return 1
        fi
        if ((10#${ver1[i]} < 10#${ver2[i]}))
        then
            return 2
        fi
    done
    return 0
}

version_compare () {
    VERSION=$(sw_vers -productVersion)

    vercomp $VERSION $1;
    case $? in
        0) op='=';;
        1) op='>';;
        2) op='<';;
    esac

    if [ $2 = '=' ] && [ $op = '=' ]; then
        return 0
    fi

    if [ $2 = '>=' ] && [ $op != '<' ]; then
        return 0
    fi

    if [ $2 = '>' ] && [ $op = '>' ]; then
        return 0
    fi

    if [ $2 = '<=' ] && [ $op != '>' ]; then
        return 0
    fi

    if [ $2 = '<' ] && [ $op = '<' ]; then
        return 0
    fi

    return 1
}

if $(version_compare '10.10.4' '>='); then
   echo '10.10.4+'
   sudo killall -HUP mDNSResponder
   exit 0
fi

if $(version_compare '10.10' '>='); then
   echo '10.10+'
   sudo discoveryutil mdnsflushcache
   exit 0
fi

if $(version_compare '10.7' '>='); then
   echo '10.7+'
   sudo killall -HUP mDNSResponder
   exit 0
fi

if $(version_compare '10.5' '>='); then
   echo '10.5+'
   sudo dscacheutil -flushcache
   exit 0
fi

echo "unsupported os version";
exit 1;