os

A reduced operating system library. Only time and clock functions remain: clock, date, difftime and time.

Removed functions

os.execute, os.exit, os.getenv, os.remove, os.rename, os.tmpname and os.setlocale are removed and are nil in this VM. File access goes through the client file API.

Functions

os.clock(): number

os.clock(): number

Returns the CPU time used by the process, in seconds. Useful to measure elapsed work, not wall-clock time.

local t0 = os.clock()
local dt = os.clock() - t0

os.date(format?: string = "%c", time?: number = os.time()): string | table

os.date(format?: string = "%c", time?: number = os.time()): string | table

Formats time (seconds since 1970-01-01 UTC) according to format.
A leading ! formats in UTC; otherwise local time is used.
"*t" (or "!*t") returns a table with the fields year, month, day, hour, min, sec, wday (1 is Sunday), yday (1 to 366) and isdst (boolean).
Otherwise the format is a C strftime string; directives below are supported. An invalid directive raises an error.

Directive	Meaning
`%a`	abbreviated weekday name
`%A`	full weekday name
`%b`	abbreviated month name
`%B`	full month name
`%c`	date and time, locale format
`%d`	day of the month (01-31)
`%H`	hour, 24-hour clock (00-23)
`%I`	hour, 12-hour clock (01-12)
`%j`	day of the year (001-366)
`%m`	month (01-12)
`%M`	minute (00-59)
`%p`	AM or PM
`%S`	second (00-61)
`%U`	week of the year, Sunday first (00-53)
`%w`	weekday, Sunday is 0 (0-6)
`%W`	week of the year, Monday first (00-53)
`%x`	date, locale format
`%X`	time, locale format
`%y`	year without century (00-99)
`%Y`	year with century
`%%`	a literal `%`

print(os.date("%Y-%m-%d %H:%M:%S"))
local t = os.date("*t")
print(t.year, t.month, t.day)

os.difftime(t2: number, t1: number): number

os.difftime(t2: number, t1: number): number

Returns the number of seconds from time t1 to time t2.

os.time(t?: table): number

os.time(t?: table): number

With no argument, returns the current time in seconds since 1970-01-01 UTC.
With a table, reads the fields year, month, day, hour (default 12), min (default 0), sec (default 0) and isdst (optional boolean) as local time and returns the corresponding timestamp.
year, month and day are required. Out-of-range fields are normalized (month 13 is January of the next year).
Returns nil if the time cannot be represented.

print(os.time({ year = 2026, month = 1, day = 1, hour = 0 }))