lua中获取系统当前的时间

--Returns the current time when called without arguments, or a time representing the date and time specified by the given table. This table must have fields year, month, and day, and may have fields hour, min, sec, and isdst (for a description of these fields,
see the os.date function).

--The returned value is a number, whose meaning depends on your system. In POSIX, Windows, and some other systems, this number counts the number of seconds since some given start time (the "epoch"). In other systems, the meaning is not specified, and the number
returned by time can be used only as an argument to date and difftime.

---获取当前时间，小时，分钟，秒

function os.time (table) end

--Returns a string or a table containing date and time, formatted according to the given string format.

--If the time argument is present, this is the time to be formatted (see the os.time function for a description of this value). Otherwise, date formats the current time.

--If format starts with '!', then the date is formatted in Coordinated Universal Time. After this optional character, if format is the string "*t", then date returns a table with the following fields: year (four digits), month (1--12), day (1--31), hour (0--23),
min (0--59), sec (0--61), wday (weekday, Sunday is 1), yday (day of the year), and isdst (daylight saving flag, a boolean).

--If format is not "*t", then date returns the date as a string, formatted according to the same rules as the C function strftime.

--When called without arguments, date returns a reasonable date and time representation that depends on the host system and on the current locale (that is, os.date() is equivalent to os.date("%c")).

----传入一定的格式比如%Y-%m-%d-%H-%M-%S以此是年-月-日-时-分-秒当然也可以是自己写的一个格式，怎样用起来方便怎样写就行了

function os.date (format , time) end

os.date("%Y-%m-%d-%H-%M-%S",os.time())直接可以获取到自定义格式的字符串