Set the Hardware Clock in Python

Python module to change system date and time

import sys
import datetime

time_tuple = ( 2012, # Year
                  9, # Month
                  6, # Day
                  0, # Hour
                 38, # Minute
                  0, # Second
                  0, # Millisecond
              )

def _win_set_time(time_tuple):
    import pywin32
    # http://timgolden.me.uk/pywin32-docs/win32api__SetSystemTime_meth.html
    # pywin32.SetSystemTime(year, month , dayOfWeek , day , hour , minute , second , millseconds )
    dayOfWeek = datetime.datetime(time_tuple).isocalendar()[2]
    pywin32.SetSystemTime( time_tuple[:2] + (dayOfWeek,) + time_tuple[2:])

def _linux_set_time(time_tuple):
    import ctypes
    import ctypes.util
    import time

    # /usr/include/linux/time.h:
    #
    # define CLOCK_REALTIME                     0
    CLOCK_REALTIME = 0

    # /usr/include/time.h
    #
    # struct timespec
    #  {
    #    __time_t tv_sec;            /* Seconds.  */
    #    long int tv_nsec;           /* Nanoseconds.  */
    #  };
    class timespec(ctypes.Structure):
        _fields_ = [("tv_sec", ctypes.c_long),
                    ("tv_nsec", ctypes.c_long)]

    librt = ctypes.CDLL(ctypes.util.find_library("rt"))

    ts = timespec()
    ts.tv_sec = int( time.mktime( datetime.datetime( *time_tuple[:6]).timetuple() ) )
    ts.tv_nsec = time_tuple[6] * 1000000 # Millisecond to nanosecond

    # http://linux.die.net/man/3/clock_settime
    librt.clock_settime(CLOCK_REALTIME, ctypes.byref(ts))

if sys.platform=='linux2':
    _linux_set_time(time_tuple)

elif  sys.platform=='win32':
    _win_set_time(time_tuple)

I don't have a windows machine so I didn't test it on windows... But you get the idea.

Python module to set local time and date

The win32api module wraps SetSystemTime to take the SYSTEMTIME structure fields as 8 separate function parameters. The time should be passed as UTC. wDayOfWeek is ignored (i.e. pass it as 0).

The win32api module wraps SetLocalTime more conveniently and idiomatically. It takes a datetime.datetime instance instead of requiring separate parameters. For example:

import datetime
import win32api

dt = datetime.datetime(2018, 1, 4, 14, 30)
win32api.SetLocalTime(dt)

The Token of the calling process must have SeSystemtimePrivilege, so generally the user needs to be an elevated administrator.

Easy way to get the correct time in python

Try ntplib for python. I've played around with it a bit and it seems pretty stable.

https://pypi.python.org/pypi/ntplib/

How Do You Programmatically Set the Hardware Clock on Linux?

Check out the rtc man-page for details, but if you are logged in as root, something like this:

#include <linux/rtc.h>
#include <sys/ioctl.h>

    struct       rtc_time {
        int         tm_sec;      
        int         tm_min;      
        int         tm_hour;     
        int         tm_mday;     
        int         tm_mon;      
        int         tm_year;     
        int         tm_wday; /* unused */
        int         tm_yday; /* unused */
        int         tm_isdst;/* unused */
    };

int fd;
struct rtc_time rt;
/* set your values here */
fd = open("/dev/rtc", O_RDONLY);
ioctl(fd, RTC_SET_TIME, &rt);
close(fd);

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