--- Operating System facilities like date, time and program execution.
-- @module os

local os = {}

---
-- Returns an approximation of the amount in seconds of CPU time used by
-- the program.
function os.clock() 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)
--   * `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")`).
function os.date(format , time) end

---
-- Returns the number of seconds from time `t1` to time `t2`. In POSIX,
-- Windows, and some other systems, this value is exactly `t2`*-*`t1`.
function os.difftime(t2, t1) end

---
-- This function is equivalent to the C function `system`. It passes
-- `command` to be executed by an operating system shell. It returns a status
-- code, which is system-dependent. If `command` is absent, then it returns
-- nonzero if a shell is available and zero otherwise.
function os.execute(command) end

---
-- Calls the C function `exit`, with an optional `code`, to terminate the
-- host program. The default value for `code` is the success code.
function os.exit(code) end

---
-- Returns the value of the process environment variable `varname`, or
-- nil if the variable is not defined.
function os.getenv(varname) end

---
-- Deletes the file or directory with the given name. Directories must be
-- empty to be removed. If this function fails, it returns nil, plus a string
-- describing the error.
function os.remove(filename) end

---
-- Renames file or directory named `oldname` to `newname`. If this function
-- fails, it returns nil, plus a string describing the error.
function os.rename(oldname, newname) end

---
-- Sets the current locale of the program. `locale` is a string specifying
-- a locale; `category` is an optional string describing which category to
-- change: `"all"`, `"collate"`, `"ctype"`, `"monetary"`, `"numeric"`, or
-- `"time"`; the default category is `"all"`. The function returns the name
-- of the new locale, or nil if the request cannot be honored.
-- If `locale` is the empty string, the current locale is set to an
-- implementation-defined native locale. If `locale` is the string "`C`",
-- the current locale is set to the standard C locale.
-- When called with nil as the first argument, this function only returns
-- the name of the current locale for the given category.
function os.setlocale(locale , category) end

---
-- 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`.
function os.time(table) end

---
-- Returns a string with a file name that can be used for a temporary
-- file. The file must be explicitly opened before its use and explicitly
-- removed when no longer needed.
-- On some systems (POSIX), this function also creates a file with that
-- name, to avoid security risks. (Someone else might create the file with
-- wrong permissions in the time between getting the name and creating the
-- file.) You still have to open the file to use it and to remove it (even
-- if you do not use it).
-- When possible, you may prefer to use `io.tmpfile`, which automatically
-- removes the file when the program ends.
function os.tmpname() end

return os