diff --git a/acme.sh b/acme.sh
index dd24899c..81f170b7 100755
--- a/acme.sh
+++ b/acme.sh
@@ -1,5 +1,5 @@
-#!/usr/bin/env bash
-VER=2.2.1
+#!/usr/bin/env sh
+VER=2.2.2
 
 PROJECT_NAME="acme.sh"
 
@@ -28,6 +28,13 @@ if [ -z "$AGREEMENT" ] ; then
 fi
 
 
+
+_URGLY_PRINTF=""
+if [ "$(printf '\x41')" != 'A' ] ; then
+  _URGLY_PRINTF=1
+fi
+
+
 _info() {
   if [ -z "$2" ] ; then
     echo "[$(date)] $1"
@@ -84,18 +91,72 @@ _exists(){
   return $ret
 }
 
+#a + b
+_math(){
+  expr "$@"
+}
+
+_h_char_2_dec() {
+  _ch=$1
+  case "${_ch}" in
+    a|A)
+      echo -n 10
+        ;;
+    b|B)
+      echo -n 11
+        ;;
+    c|C)
+      echo -n 12
+        ;;
+    d|D)
+      echo -n 13
+        ;;
+    e|E)
+      echo -n 14
+        ;;
+    f|F)
+      echo -n 15
+        ;;
+    *)
+      echo -n $_ch
+        ;;
+  esac       
+
+}
+
 _h2b() {
   hex=$(cat)
   i=1
   j=2
+  if _exists let ; then
+    uselet="1"
+  fi
+  _debug uselet "$uselet"
+  _debug _URGLY_PRINTF "$_URGLY_PRINTF"
   while [ '1' ] ; do
-    h=$(printf $hex | cut -c $i-$j)
-    if [ -z "$h" ] ; then
-      break;
+    if [ -z "$_URGLY_PRINTF" ] ; then
+      h=$(printf $hex | cut -c $i-$j)
+      if [ -z "$h" ] ; then
+        break;
+      fi
+      printf "\x$h"
+    else
+      ic=$(printf $hex | cut -c $i)
+      jc=$(printf $hex | cut -c $j)
+      if [ -z "$ic$jc" ] ; then
+        break;
+      fi
+      ic="$(_h_char_2_dec $ic)"
+      jc="$(_h_char_2_dec $jc)"
+      printf '\'"$(printf %o "$(_math $ic \* 16 + $jc)")"
     fi
-    printf "\x$h"
-    let "i+=2"
-    let "j+=2"
+    if [ "$uselet" ] ; then
+      let "i+=2" >/dev/null
+      let "j+=2" >/dev/null
+    else
+      i="$(_math $i + 2)"
+      j="$(_math $j + 2)"
+    fi    
   done
 }
 
@@ -133,7 +194,7 @@ _getfile() {
     _err "Can not find start line: $startline"
     return 1
   fi
-  let "i+=1"
+  i="$(_math $i + 1)"
   _debug i $i
   
   j="$(grep -n --  "$endline"  $filename | cut -d : -f 1)"
@@ -141,7 +202,7 @@ _getfile() {
     _err "Can not find end line: $endline"
     return 1
   fi
-  let "j-=1"
+  j="$(_math $j - 1)"
   _debug j $j
   
   sed -n $i,${j}p  "$filename"
@@ -427,7 +488,8 @@ _calcjwk() {
     _debug2 e "$e"
     
     modulus=$(openssl rsa -in $keyfile -modulus -noout | cut -d '=' -f 2 )
-    n=$(echo $modulus| _h2b | _base64 | _urlencode )
+    _debug2 modulus "$modulus"
+    n=$(echo -n $modulus| _h2b | _base64 | _urlencode )
     jwk='{"e": "'$e'", "kty": "RSA", "n": "'$n'"}'
     _debug2 jwk "$jwk"
     
@@ -440,28 +502,28 @@ _calcjwk() {
     _debug2 crv $crv
     
     pubi="$(openssl ec  -in $keyfile  -noout -text 2>/dev/null | grep -n pub: | cut -d : -f 1)"
+    pubi=$(_math $pubi + 1)
     _debug2 pubi $pubi
-    let "pubi=pubi+1"
     
     pubj="$(openssl ec  -in $keyfile  -noout -text 2>/dev/null | grep -n "ASN1 OID:"  | cut -d : -f 1)"
+    pubj=$(_math $pubj + 1)
     _debug2 pubj $pubj
-    let "pubj=pubj-1"
     
     pubtext="$(openssl ec  -in $keyfile  -noout -text 2>/dev/null | sed  -n "$pubi,${pubj}p" | tr -d " \n\r")"
     _debug2 pubtext "$pubtext"
     
     xlen="$(printf "$pubtext" | tr -d ':' | wc -c)"
-    let "xlen=xlen/4"
+    xlen=$(_math $xlen / 4)
     _debug2 xlen $xlen
-    
-    let "xend=xlen+1"
+
+    xend=$(_math $xend + 1)
     x="$(printf $pubtext | cut -d : -f 2-$xend)"
     _debug2 x $x
     
     x64="$(printf $x | tr -d : | _h2b | _base64 | _urlencode)"
     _debug2 x64 $x64
-    
-    let "xend+=1"
+
+    xend=$(_math $xend + 1)
     y="$(printf $pubtext | cut -d : -f $xend-10000)"
     _debug2 y $y
     
@@ -658,12 +720,12 @@ _startserver() {
   _debug "_NC" "$_NC"
 #  while true ; do
     if [ "$DEBUG" ] ; then
-      if ! echo -e -n "HTTP/1.1 200 OK\r\n\r\n$content" | $_NC -p $Le_HTTPPort ; then
-        echo -e -n "HTTP/1.1 200 OK\r\n\r\n$content" | $_NC $Le_HTTPPort ;
+      if ! printf "HTTP/1.1 200 OK\r\n\r\n$content" | $_NC -p $Le_HTTPPort ; then
+        printf "HTTP/1.1 200 OK\r\n\r\n$content" | $_NC $Le_HTTPPort ;
       fi
     else
-      if ! echo -e -n "HTTP/1.1 200 OK\r\n\r\n$content" | $_NC -p $Le_HTTPPort > /dev/null 2>&1; then
-        echo -e -n "HTTP/1.1 200 OK\r\n\r\n$content" | $_NC $Le_HTTPPort > /dev/null 2>&1
+      if ! printf "HTTP/1.1 200 OK\r\n\r\n$content" | $_NC -p $Le_HTTPPort > /dev/null 2>&1; then
+        printf "HTTP/1.1 200 OK\r\n\r\n$content" | $_NC $Le_HTTPPort > /dev/null 2>&1
       fi      
     fi
     if [ "$?" != "0" ] ; then
@@ -1122,7 +1184,7 @@ issue() {
         _currentRoot="$_w"
       fi
       _debug "_currentRoot" "$_currentRoot"
-      let "_index+=1"
+      _index=$(_math $_index + 1)
       
       vtype="$VTYPE_HTTP"
       if _startswith "$_currentRoot" "dns" ; then
@@ -1317,7 +1379,7 @@ issue() {
     fi
     
     while [ "1" ] ; do
-      let "waittimes+=1"
+      waittimes=$(_math $waittimes + 1)
       if [ "$waittimes" -ge "$MAX_RETRY_TIMES" ] ; then
         _err "$d:Timeout"
         _clearupwebbroot "$_currentRoot" "$removelevel" "$token"
@@ -1423,8 +1485,8 @@ issue() {
   fi
   
   _setopt "$DOMAIN_CONF"  "Le_RenewalDays"      "="  "$Le_RenewalDays"
-  
-  let "Le_NextRenewTime=Le_CertCreateTime+Le_RenewalDays*24*60*60"
+
+  Le_NextRenewTime=$(_math $Le_CertCreateTime + $Le_RenewalDays \* 24 \* 60 \* 60)
   _setopt "$DOMAIN_CONF"  "Le_NextRenewTime"      "="  "$Le_NextRenewTime"
   
   Le_NextRenewTimeStr=$( _time2str $Le_NextRenewTime )
@@ -1787,6 +1849,19 @@ _precheck() {
   return 0
 }
 
+_setShebang() {
+  _file="$1"
+  _shebang="$2"
+  if [ -z "$_shebang" ] ; then
+    _err "Usage: file shebang"
+    return 1
+  fi
+  cp "$_file" "$_file.tmp"
+  echo "$_shebang" > "$_file"
+  sed -n 2,99999p  "$_file.tmp" >> "$_file"
+  rm -f "$_file.tmp"  
+}
+
 install() {
 
   if ! _initpath ; then
@@ -1880,7 +1955,21 @@ install() {
   fi
   
   installcronjob
-  
+
+  if [ -z "$NO_DETECT_SH" ] ; then
+    #Modify shebang
+    if _exists bash ; then
+      _info "Good, bash is installed, change the shebang to use bash as prefered."
+      _shebang='#!/usr/bin/env bash'
+      _setShebang "$LE_WORKING_DIR/$PROJECT_ENTRY" "$_shebang"
+      if [ -d "$LE_WORKING_DIR/dnsapi" ] ; then
+        for _apifile in $(ls "$LE_WORKING_DIR/dnsapi/"*.sh) ; do
+          _setShebang "$_apifile" "$_shebang"
+        done
+      fi
+    fi
+  fi
+
   _info OK
 }
 
diff --git a/dnsapi/dns_cf.sh b/dnsapi/dns_cf.sh
index c5eaac46..2aac3404 100755
--- a/dnsapi/dns_cf.sh
+++ b/dnsapi/dns_cf.sh
@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/usr/bin/env sh
 
 
 #
@@ -112,7 +112,7 @@ _get_root() {
       return 1
     fi
     p=$i
-    let "i+=1"
+    i=$(expr $i + 1)
   done
   return 1
 }
diff --git a/dnsapi/dns_cx.sh b/dnsapi/dns_cx.sh
index 3ebb7bfe..070a2ad6 100644
--- a/dnsapi/dns_cx.sh
+++ b/dnsapi/dns_cx.sh
@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/usr/bin/env sh
 
 # Cloudxns.com Domain api
 #
@@ -159,7 +159,7 @@ _get_root() {
       return 1
     fi
     p=$i
-    let "i+=1"
+    i=$(expr $i + 1)
   done
   return 1
 }
diff --git a/dnsapi/dns_dp.sh b/dnsapi/dns_dp.sh
index f47d4bd5..510384ab 100644
--- a/dnsapi/dns_dp.sh
+++ b/dnsapi/dns_dp.sh
@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/usr/bin/env sh
 
 # Dnspod.cn Domain api
 #
@@ -165,7 +165,7 @@ _get_root() {
       return 1
     fi
     p=$i
-    let "i+=1"
+    i=$(expr $i + 1)
   done
   return 1
 }
diff --git a/dnsapi/dns_myapi.sh b/dnsapi/dns_myapi.sh
index 3c5b8651..f06cc1e6 100644
--- a/dnsapi/dns_myapi.sh
+++ b/dnsapi/dns_myapi.sh
@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/usr/bin/env sh
 
 #Here is a sample custom api script.
 #This file name is "dns_myapi.sh"