diff --git a/prod/upload/combine.lua b/prod/upload/combine.lua
index feb50e6..3d82946 100644
--- a/prod/upload/combine.lua
+++ b/prod/upload/combine.lua
@@ -13,14 +13,13 @@ local origin = {}
 for i = 1, len do
     origin[i] = file_dir .. "/" .. data[i] .. " "
 end
--- linux
-local magick = "/usr/local/ImageMagick/bin/magick"
-local tmp = io.open(magick,"r")
-if tmp == nil then
-    -- mac os
-    magick = "/usr/local/bin/magick"
-else
-    io.close(tmp)
+-- 从 nginx 变量取
+local magick = ngx.var.magick
+
+if not magick then
+    ngx.status = 500
+    ngx.say("image magick not found.")
+    return
 end
 
 local result, _, code = os.execute(magick .. " convert -append " .. table.concat(origin, " ") .. " " .. combined)
diff --git a/prod/upload/upload.lua b/prod/upload/upload.lua
index b6f176b..9dc9f36 100644
--- a/prod/upload/upload.lua
+++ b/prod/upload/upload.lua
@@ -51,6 +51,7 @@ while true do
             table.insert(files, file_name)
         end
         -- 这里要重置一下file_name，否则后面的文件保存时会导致前面已保存的文件变成空文件
+        -- file:flush() 和 io.flush() 都没效果
         file_name = nil
         file = nil
     elseif typ == "eof" then
diff --git a/test/test_magick.lua b/test/test_magick.lua
index 3785568..9e5661f 100644
--- a/test/test_magick.lua
+++ b/test/test_magick.lua
@@ -1,12 +1,21 @@
-local magick = "/usr/local/ImageMagick/bin/magick"
-local tmp = io.open(magick,"r")
-if tmp == nil then
-    -- in mac os
-    magick = "/usr/local/bin/magick"
-else
-    io.close(tmp)
+-- read from nginx var config
+local magick = ngx.var.magick
+ngx.log(ngx.ERR, 'var', magick)
+-- or use which command to get
+if not magick then
+    local exec = io.popen("which magick")
+    local tmp = exec:read("*a")
+    magick = string.gsub(tmp, "%s+", "")
+    exec:close()
 end
-print(magick)
+if not magick then
+    ngx.status = 500
+    ngx.say("image magick not found.")
+    return
+end
+
+ngx.say(magick)
+
 
 --local origin = {
 --    "/Users/moicen/Music/alchemy/Song-of-joy.png",