--- Returns CPU time used by program in seconds.
function clock()
--- Returns a string or table containing date and time, "*t" returns a table.
function date([format [, time]])
--- Returns number of seconds from time t1 to time t2.
function difftime(t2, t1)
--- Executes command using C function system, returns status code.
function execute(command)
--- Terminates host program with optional code, default is success code.
function exit([code])
--- Returns value of environment variable varname. nil if not defined.
function getenv(varname)
--- Deletes file with given name, nil if fails.
function remove(filename)
--- Renames file oldname to newname, nil if fails.
function rename(oldname, newname)
--- Set current locale of program, returns name of new locate or nil.
function setlocale(locale [, category])
--- Returns current time(usually seconds) or time as represented by table.
function time([table])
---
-- Returns a string with a filename for a temporary file(dangerous! tmpfile is
-- better).
function tmpname()