popen solution

conf/local_macos/test.conf

@@ -9,5 +9,9 @@ server {
     location /api/ngx/test/co {
         content_by_lua_file $resty_loc/nginx/scripts/tests/co.lua;
     }
+
+    location /api/ngx/test/popen {
+        content_by_lua_file $resty_loc/nginx/scripts/tests/popen.lua;
+    }
 }
 

test_scripts/popen.lua

@@ -0,0 +1,4 @@
+io.popen("sleep 3; echo hello>/tmp/foo.txt")
+
+ngx.say("main")
+