update as.sh to 3.0.4.1

as.sh

@@ -8,10 +8,10 @@
 
 # program : Arthas
 #  author : Core Engine @ Taobao.com
-#    date : 2018-11-12
+#    date : 2018-11-19
 
 # current arthas script version
-ARTHAS_SCRIPT_VERSION=3.0.4.1
+ARTHAS_SCRIPT_VERSION=3.0.4.2
 
 # define arthas's home
 ARTHAS_HOME=${HOME}/.arthas
@@ -111,6 +111,68 @@ check_permission()
 }
 
 
+# SYNOPSIS
+#   rreadlink <fileOrDirPath>
+# DESCRIPTION
+#   Resolves <fileOrDirPath> to its ultimate target, if it is a symlink, and
+#   prints its canonical path. If it is not a symlink, its own canonical path
+#   is printed.
+#   A broken symlink causes an error that reports the non-existent target.
+# LIMITATIONS
+#   - Won't work with filenames with embedded newlines or filenames containing 
+#     the string ' -> '.
+# COMPATIBILITY
+#   This is a fully POSIX-compliant implementation of what GNU readlink's
+#    -e option does.
+# EXAMPLE
+#   In a shell script, use the following to get that script's true directory of origin:
+#     trueScriptDir=$(dirname -- "$(rreadlink "$0")")
+rreadlink() ( # Execute the function in a *subshell* to localize variables and the effect of `cd`.
+
+  target=$1 fname= targetDir= CDPATH=
+
+  # Try to make the execution environment as predictable as possible:
+  # All commands below are invoked via `command`, so we must make sure that
+  # `command` itself is not redefined as an alias or shell function.
+  # (Note that command is too inconsistent across shells, so we don't use it.)
+  # `command` is a *builtin* in bash, dash, ksh, zsh, and some platforms do not 
+  # even have an external utility version of it (e.g, Ubuntu).
+  # `command` bypasses aliases and shell functions and also finds builtins 
+  # in bash, dash, and ksh. In zsh, option POSIX_BUILTINS must be turned on for
+  # that to happen.
+  { \unalias command; \unset -f command; } >/dev/null 2>&1
+  [ -n "$ZSH_VERSION" ] && options[POSIX_BUILTINS]=on # make zsh find *builtins* with `command` too.
+
+  while :; do # Resolve potential symlinks until the ultimate target is found.
+      [ -L "$target" ] || [ -e "$target" ] || { command printf '%s\n' "ERROR: '$target' does not exist." >&2; return 1; }
+      command cd "$(command dirname -- "$target")" # Change to target dir; necessary for correct resolution of target path.
+      fname=$(command basename -- "$target") # Extract filename.
+      [ "$fname" = '/' ] && fname='' # !! curiously, `basename /` returns '/'
+      if [ -L "$fname" ]; then
+        # Extract [next] target path, which may be defined
+        # *relative* to the symlink's own directory.
+        # Note: We parse `ls -l` output to find the symlink target
+        #       which is the only POSIX-compliant, albeit somewhat fragile, way.
+        target=$(command ls -l "$fname")
+        target=${target#* -> }
+        continue # Resolve [next] symlink target.
+      fi
+      break # Ultimate target reached.
+  done
+  targetDir=$(command pwd -P) # Get canonical dir. path
+  # Output the ultimate target's canonical path.
+  # Note that we manually resolve paths ending in /. and /.. to make sure we have a normalized path.
+  if [ "$fname" = '.' ]; then
+    command printf '%s\n' "${targetDir%/}"
+  elif  [ "$fname" = '..' ]; then
+    # Caveat: something like /var/.. will resolve to /private (assuming /var@ -> /private/var), i.e. the '..' is applied
+    # AFTER canonicalization.
+    command printf '%s\n' "$(command dirname -- "${targetDir}")"
+  else
+    command printf '%s\n' "${targetDir%/}/$fname"
+  fi
+)
+
 # reset arthas work environment
 # reset some options for env
 reset_for_env()
@@ -122,19 +184,36 @@ reset_for_env()
 
     # if env define the JAVA_HOME, use it first
     # if is alibaba opts, use alibaba ops's default JAVA_HOME
-    [ -z "${JAVA_HOME}" ] && JAVA_HOME=/opt/taobao/java
+    [ -z "${JAVA_HOME}" ] && [ -d /opt/taobao/java ] && JAVA_HOME=/opt/taobao/java
+
+    if [[ (-z "${JAVA_HOME}") && ( -e "/usr/libexec/java_home") ]]; then
+        # for mac
+        JAVA_HOME=`/usr/libexec/java_home`
+    fi
+
+    if [ -z "${JAVA_HOME}" ]; then
+        # try to find JAVA_HOME from java command
+        local JAVA_COMMAND_PATH=$( rreadlink $(type -p java) )
+        JAVA_HOME=$(echo "$JAVA_COMMAND_PATH" | sed -n 's/\/bin\/java$//p')
+    fi
 
     # iterater throught candidates to find a proper JAVA_HOME at least contains tools.jar which is required by arthas.
     if [ ! -d "${JAVA_HOME}" ]; then
         JAVA_HOME_CANDIDATES=($(ps aux | grep java | grep -v 'grep java' | awk '{print $11}' | sed -n 's/\/bin\/java$//p'))
         for JAVA_HOME_TEMP in ${JAVA_HOME_CANDIDATES[@]}; do
             if [ -f "${JAVA_HOME_TEMP}/lib/tools.jar" ]; then
-                JAVA_HOME=${JAVA_HOME_TEMP}
+                JAVA_HOME=`rreadlink "${JAVA_HOME_TEMP}"`
                 break
             fi
         done
     fi
 
+    if [ -z "${JAVA_HOME}" ]; then
+        exit_on_err 1 "Can not find JAVA_HOME, please set \$JAVA_HOME bash env first."
+    fi
+
+    echo "JAVA_HOME: ${JAVA_HOME}"
+
     # maybe 1.8.0_162 , 11-ea
     local JAVA_VERSION
 
@@ -484,7 +563,7 @@ active_console()
             # Windows/system32/telnet.exe can not run in Cygwin/MinGw
             echo "It seems that current bash is under Windows. $(command -v telnet) can not run under bash."
             echo "Please start cmd.exe from Windows start menu, and then run telnet ${TARGET_IP} ${TELNET_PORT} to connect to target process."
-            echo "Or visit http://localhost:8563/ to connect to target process."
+            echo "Or visit http://127.0.0.1:8563/ to connect to target process."
             return 1
         fi
         echo "telnet connecting to arthas server... current timestamp is `date +%s`"