Operating system (OS) standard library.
Includes functions for file manipulation, for getting the current date and time, and other facilities related to the operating system.
|clock ()||Returns an approximation of the amount in seconds of CPU time used by the program.|
|date (format, time)||Returns a string or a table containing date and time, formatted according
to the given string
|difftime (t2, t1)||Returns the number of seconds from time
|execute (command)||This function is equivalent to the C function
|exit (code)||Calls the C function
|getenv (varname)||Returns the value of the process environment variable
|remove (filename)||Deletes the file or directory with the given name.|
|rename (oldname, newname)||Renames file or directory named
|setlocale (locale, category)||Sets the current locale of the program.|
|sleep (seconds)||Sleeps for a number of seconds.|
|storage (address, length)||Gets data from storage.|
|time (table)||Returns the current time when called without arguments, or a time representing the date and time specified by the given table.|
|tmpname ()||Returns a string with a file name that can be used for a temporary file.|
- clock ()
- Returns an approximation of the amount in seconds of CPU time used by the program.
- date (format, time)
Returns a string or a table containing date and time, formatted according
to the given string
timeargument is present, this is the time to be formatted (see the
os.timefunction for a description of this value). Otherwise,
dateformats the current time.
formatstarts with '
!', then the date is formatted in Coordinated Universal Time. After this optional character, if
formatis the string "
datereturns a table with the following fields:
wday(weekday, Sunday is 1)
yday(day of the year)
isdst(daylight saving flag, a boolean).
formatis not "
datereturns the date as a string, formatted according to the same rules as the C function
strftime. When called without arguments,
datereturns a reasonable date and time representation that depends on the host system and on the current locale (that is,
os.date()is equivalent to
- difftime (t2, t1)
Returns the number of seconds from time
t2. In POSIX, Windows, and some other systems, this value is exactly
- execute (command)
This function is equivalent to the C function
system(). It passes
commandto be executed by an operating system shell. It returns a status code, which is system-dependent. If
commandis absent, then it returns nonzero if a shell is available and zero otherwise.
The command to pass to the
- command string The command to pass to the
- exit (code)
Calls the C function
exit, with an optional
code, to terminate the host program. The default value for
codeis the success code.
- getenv (varname)
Returns the value of the process environment variable
varname, or nil if the variable is not defined.
- 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.
- rename (oldname, newname)
Renames file or directory named
newname. If this function fails, it returns nil, plus a string describing the error.
- setlocale (locale, category)
Sets the current locale of the program.
localeis a string specifying a locale;
categoryis an optional string describing which category to change:
"time"; the default category is
"all". The function returns the name of the new locale, or nil if the request cannot be honored. If
localeis the empty string, the current locale is set to an implementation-defined native locale. If
localeis 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.
- sleep (seconds)
Sleeps for a number of seconds.
- seconds int Integer number of seconds to sleep.
- storage (address, length)
Gets data from storage.
- address int The start address of the storage.
- length int The number of bytes to get.
lengthbytes of data from the specified
- 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
day, and may have fields
isdst(for a description of these fields, see the
os.datefunction). 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
timecan be used only as an argument to
- 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.