语法: str = ngx.utctime()
环境: init_worker_by_lua*, set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*, body_filter_by_lua*, log_by_lua*, ngx.timer.*
返回nginx时间缓存(不像Lua的os.date函数，该时间不涉及系统调用)的当前时间戳(格式：yyyy-mm-dd hh:mm:ss)。
这是个UTC时间。
English Source
syntax: str = ngx.utctime()
context: init_worker_by_lua*, set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*, body_filter_by_lua*, log_by_lua*, ngx.timer.*
Returns the current time stamp (in the format yyyy-mm-dd hh:mm:ss) of the nginx cached time (no syscall involved unlike Lua's os.date function).
This is the UTC time.