os

The os library in Yahaha provides functions for interacting with the operating system, such as getting the current time under UTC format. It has been sandboxed and does not allow you to perform any system altering operations such as accessing environmental variables and executing system commands.

Functions

number os.clock()

ReturnsThe clock.

Returns the CPU time used by the program since it started running, in seconds.

-- Measure the time taken to execute a loop that counts from 1 to 1000000
local start = os.clock()
for i = 1, 1000000 do
-- Do something here...
end
local elapsed = os.clock() - start
-- Print the elapsed time
print("Elapsed time:", elapsed, "seconds")

In this example, we use os.clock() to measure the time taken to execute a loop that counts from 1 to 1000000. We store the starting time in the start variable using os.clock(), and then execute the loop. After the loop has completed, we calculate the elapsed time by subtracting the starting time from the current time using os.clock() - start, and store the result in the elapsed variable. Finally, we print the elapsed time using print("Elapsed time:", elapsed, "seconds"). Note that os.clock() returns CPU time, which may not correspond directly to wall-clock time. The actual elapsed time may be longer or shorter than the CPU time depending on factors such as system load and CPU speed.

string os.date(string format, number time)

ReturnsThe date string.

Returns a formatted string representing a date and time, based on the specified format string and timestamp. If no timestamp is provided, os.date() uses the current date and time.

• format The date format.
• time The time.

-- Get the current date and time
local currentTime = os.time()
local formattedTime = os.date("%Y-%m-%d %H:%M:%S", currentTime)
-- Print the formatted time
print("Current time:", formattedTime)

In this example, we use os.time() to get the current time as a Unix timestamp, and store it in the currentTime variable. We then use os.date() to format the timestamp as a string in the format "%Y-%m-%d %H:%M:%S", which represents the year, month, day, hour, minute, and second of the timestamp. We store the formatted string in the formattedTime variable.

Finally, we print the formatted time using print("Current time:", formattedTime).

The output of this program will be a string representing the current date and time in the specified format, like this:

Current time: 2023-02-16 19:06:49

Note that the os.date() function supports a wide range of format codes for representing different parts of the date and time, such as %a for the abbreviated weekday name and %Y for the year with century as a decimal number.

%a	abbreviated weekday name (e.g., Wed)
%A	full weekday name (e.g., Wednesday)
    %b	abbreviated month name (e.g., Sep)
    %B	full month name (e.g., September)
    %c	date and time (e.g., 09/16/98 23:48:10)
    %d	day of the month (16) [01-31]
%H	hour, using a 24-hour clock (23) [00-23]
%I	hour, using a 12-hour clock (11) [01-12]
%M	minute (48) [00-59]
%m	month (09) [01-12]
%p	either "am" or "pm" (pm)
%S	second (10) [00-61]
%w	weekday (3) [0-6 = Sunday-Saturday]
%x	date (e.g., 09/16/98)
    %X	time (e.g., 23:48:10)
    %Y	full year (1998)
    %y	two-digit year (98) [00-99]
%%	the character `%´

number os.difftime(number t2, number t1)

ReturnsThe result.

Function that calculates the difference in seconds between two timestamps. This function takes two timestamps as arguments, t2 and t1, and returns the difference between them in seconds as a floating-point number.

• t2 The later time.
• t1 The earlier time.

-- Get two timestamps and calculate the difference between them
local currentTime = os.time()
local earlierTime = os.time({year=2023, month=2, day=1, hour=0, min=0, sec=0})
local timeDifference = os.difftime(currentTime, earlierTime)
-- Print the time difference in seconds
print("Time difference:", timeDifference, "seconds")

In this example, we use os.time() to get the current time as a Unix timestamp, and store it in the currentTime variable. We also use os.time() to create another timestamp, earlierTime, which represents February 1, 2023 at midnight. We store this timestamp in the earlierTime variable.

We then use os.difftime() to calculate the difference in seconds between the two timestamps, currentTime and earlierTime, and store the result in the timeDifference variable.

Finally, we print the time difference in seconds using print("Time difference:", timeDifference, "seconds").

The output of this program will be the time difference between the two timestamps in seconds, which will depend on the current time when the program is run. For example, if the current time is February 16, 2023 at 19:28 PM, the output might look like this:

Time difference: 1366071 seconds

number os.time()

ReturnsThe time.

Function that returns the current time as a Unix timestamp, which represents the number of seconds that have elapsed since January 1, 1970. This function can also be used to convert a date and time specified as a table into a Unix timestamp.

-- Get the current time as a timestamp
local currentTime = os.time()
-- Convert a date and time to a timestamp
local timestamp = os.time({year=2023, month=2, day=16, hour=15, min=0, sec=0})
-- Print the timestamps
print("Current time:", currentTime)
print("Timestamp for Feb 16, 2023 at 8:00 PM:", timestamp)

In this example, we use os.time() to get the current time as a Unix timestamp, and store it in the currentTime variable. We then create a new table that specifies a date and time of February 16, 2023 at 8:00 PM, and pass it to os.time() to convert it to a Unix timestamp. We store the resulting timestamp in the timestamp variable.

Finally, we print the two timestamps using print("Current time:", currentTime) and print("Timestamp for Feb 16, 2023 at 8:00 PM:", timestamp).

The output of this program will be two Unix timestamps representing the current time and the specified date and time, like this:

Current time: 1676576948
Timestamp for Feb 16, 2023 at 8:00 PM: 1676559600

Note that the table passed to os.time() must have the required fields for the date and time. The fields can include year, month, day, hour, min, sec, and isdst. If the isdst field is not provided, Lua assumes that daylight saving time is not in effect. If the table contains only a subset of the required fields, os.time() will use default values for the missing fields.