Convert install.sh from bash to posix shell

install.sh

@@ -1,14 +1,14 @@
-#!/bin/bash
+#!/bin/sh
 set -e
 
 WORKDIR="$(mktemp -d)"
-SERVERS=(114.114.114.114 114.114.115.115 223.5.5.5 119.29.29.29)
+SERVERS="114.114.114.114 114.114.115.115 223.5.5.5 119.29.29.29"
 # Others: 223.6.6.6 119.28.28.28
 # Not using best possible CDN pop: 1.2.4.8 210.2.4.8
 # Broken?: 180.76.76.76
 
-CONF_WITH_SERVERS=(accelerated-domains.china google.china apple.china)
-CONF_SIMPLE=(bogus-nxdomain.china)
+CONF_WITH_SERVERS="accelerated-domains.china google.china apple.china"
+CONF_SIMPLE="bogus-nxdomain.china"
 
 echo "Downloading latest configurations..."
 git clone --depth=1 https://gitee.com/felixonmars/dnsmasq-china-list.git "$WORKDIR"
@@ -21,17 +21,17 @@ git clone --depth=1 https://gitee.com/felixonmars/dnsmasq-china-list.git "$WORKD
 #git clone --depth=1 http://repo.or.cz/dnsmasq-china-list.git "$WORKDIR"
 
 echo "Removing old configurations..."
-for _conf in "${CONF_WITH_SERVERS[@]}" "${CONF_SIMPLE[@]}"; do
+for _conf in $CONF_WITH_SERVERS $CONF_SIMPLE; do
   rm -f /etc/dnsmasq.d/"$_conf"*.conf
 done
 
 echo "Installing new configurations..."
-for _conf in "${CONF_SIMPLE[@]}"; do
+for _conf in $CONF_SIMPLE; do
   cp "$WORKDIR/$_conf.conf" "/etc/dnsmasq.d/$_conf.conf"
 done
 
-for _server in "${SERVERS[@]}"; do
-  for _conf in "${CONF_WITH_SERVERS[@]}"; do
+for _server in $SERVERS; do
+  for _conf in $CONF_WITH_SERVERS; do
     cp "$WORKDIR/$_conf.conf" "/etc/dnsmasq.d/$_conf.$_server.conf"
   done
 
@@ -45,7 +45,7 @@ elif hash service 2>/dev/null; then
   service dnsmasq restart
 elif hash rc-service 2>/dev/null; then
   rc-service dnsmasq restart
-elif hash busybox 2>/dev/null && [[ -d "/etc/init.d" ]]; then
+elif hash busybox 2>/dev/null && [ -d "/etc/init.d" ]; then
   /etc/init.d/dnsmasq restart
 else
   echo "Now please restart dnsmasq since I don't know how to do it."