Lua os standard library

Version: stable

FUNCTION
os.clock() amount of elapsed/CPU time used (depending on OS)
os.date() formats a date/time string
os.difftime() calculates a time difference in seconds
os.execute() executes an operating system command
os.exit() attempts to terminate the process
os.getenv() returns an operating system environment variable
os.remove() deletes a file
os.rename() renames a file
os.setlocale() sets the current locale to the supplied locale
os.time() returns the current time or calculates the time in seconds from a table
os.tmpname() returns a name for a temporary file

Functions

os.clock()

os.clock()

Returns an approximation of the amount in seconds of CPU time used by the program.

PARAMETERS

None

os.date()

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 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")).

PARAMETERS

[format]
[time]

os.difftime()

os.difftime(t2,t1)

Returns the number of seconds from time t1 to time t2. In POSIX, Windows, and some other systems, this value is exactly t2-t1.

PARAMETERS

t2
t1

os.execute()

os.execute([command])

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.

PARAMETERS

[command]

os.exit()

os.exit([code])

Calls the C function exit, with an optional code, to terminate the host program. The default value for code is the success code. Calling os.exit will do a hard exit which will not run the engine shutdown code. This may cause crashes on exit. The recommended way to terminate your game is by using the exit message which does a graceful shutdown. msg.post("@system:", "exit", {code = 0})

PARAMETERS

[code]

os.getenv()

os.getenv(varname)

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

PARAMETERS

varname

os.remove()

os.remove(filename)

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.

PARAMETERS

filename

os.rename()

os.rename(oldname,newname)

Renames file or directory named oldname to newname. If this function fails, it returns nil, plus a string describing the error.

PARAMETERS

oldname
newname

os.setlocale()

os.setlocale(locale,[category])

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.

PARAMETERS

locale
[category]

os.time()

os.time([table])

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.

PARAMETERS

[table]

os.tmpname()

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 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.

PARAMETERS

None