os.time ([table]) Returns the current time when called without arguments, or a time representing the local date and time specified by the given table. This table must have fields year, month, and day, and may have fields hour (default is 12), min (default is 0), sec (default is 0), and isdst (default is nil). Other fields are ignored. For a description of these fields, see the os.date function. The values in these fields do not need to be inside their valid ranges. For instance, if sec is -

os.tmpname () 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 POSIX systems, 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 poss

os.setlocale (locale [, category]) Sets the current locale of the program. locale is a system-dependent 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

os.rename (oldname, newname) Renames the file or directory named oldname to newname. If this function fails, it returns nil, plus a string describing the error and the error code. Otherwise, it returns true.

os.remove (filename) Deletes the file (or empty directory, on POSIX systems) with the given name. If this function fails, it returns nil, plus a string describing the error and the error code. Otherwise, it returns true.

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

os.exit ([code [, close]]) Calls the ISO C function exit to terminate the host program. If code is true, the returned status is EXIT_SUCCESS; if code is false, the returned status is EXIT_FAILURE; if code is a number, the returned status is this number. The default value for code is true. If the optional second argument close is true, closes the Lua state before exiting.

os.execute ([command]) This function is equivalent to the ISO C function system. It passes command to be executed by an operating system shell. Its first result is true if the command terminated successfully, or nil otherwise. After this first result the function returns a string plus a number, as follows: "exit": the command terminated normally; the following number is the exit status of the command. "signal": the command was terminated by a signal; the following number is the signal t

os.date ([format [, time]]) 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 fiel

os.difftime (t2, t1) Returns the difference, in seconds, from time t1 to time t2 (where the times are values returned by os.time). In POSIX, Windows, and some other systems, this value is exactly t2-t1.