Python Tips

Time , Timezone

The time module provides various time-related functions. For related functionality, see also the datetime and calendar modules.

An explanation of some terminology :

• epoch
the point where the time starts, and is platform dependent. For Unix, the epoch is January 1, 1970, 00:00:00 (UTC). Use time.gmtime(0) to get the epoch on a platform.
• seconds since the epoch
the total number of elapsed seconds since the epoch
• UTC ( Coordinated Universal Time )
Greenwich Mean Time, or GMT.
• DST ( Daylight Saving Time )
DST rules are magic (determined by local law)
• the precision of time() and sleep()
time() returns the most accurate time available (using Unix gettimeofday() where available), and sleep() will accept a time with a nonzero fraction (Unix select() is used to implement this, where available).
• Use the following functions to convert between time representations:

From	To	Use
seconds since the epoch	struct_time in UTC	gmtime()
seconds since the epoch	struct_time in local time	localtime()
struct_time in UTC	seconds since the epoch	calendar.timegm()
struct_time in local time	seconds since the epoch	mktime()

• time.gmtime([secs])
Convert a time expressed in seconds since the epoch to a struct_time in UTC in which the dst flag is always zero. If secs is not provided or None, the current time as returned by time() is used.

>>> time.gmtime()

time.struct_time(tm_year=2020, tm_mon=2, tm_mday=22, tm_hour=6, tm_min=24, tm_sec=20, tm_wday=5, tm_yday=53, tm_isdst=0)

• time.localtime([secs]
Like gmtime() but converts to local time. If secs is not provided or None, the current time as returned by time() is used. The dst flag is set to 1 when DST applies to the given time.

>>> time.localtime()

time.struct_time(tm_year=2020, tm_mon=2, tm_mday=22, tm_hour=14, tm_min=24, tm_sec=20, tm_wday=5, tm_yday=53, tm_isdst=0)

platform — Access to underlying platform’s identifying data

import platform	Ubuntu 18.04	Raspbian Buster Lite
platform.platform()	'Linux-5.3.0-40-generic-x86_64-with-Ubuntu-18.04-bionic'	'Linux-4.19.97+-armv6l-with-debian-10.3'
platform.system()	'Linux'	'Linux'
platform.release()	'5.3.0-40-generic'	'4.19.97+'
platform.machine()	'x86_64'	'armv6l'
platform.version()	'#32~18.04.1-Ubuntu SMP Mon Feb 3 14:05:59 UTC 2020'	'#1294 Thu Jan 30 13:10:54 GMT 2020'

syslog — Unix syslog library routines

This module provides an interface to the Unix syslog library routines.
syslog(priority, format) generates a log message, which will be distributed by syslogd(8).

The priority argument is formed by ORing together a facility(a default of LOG_USER) value and a level(a default of LOG_INFO) value.

• facility
The facility argument is used to specify what type of program is logging the message.
• level
• 
  LOG_EMERG
• 
  LOG_ALERT
• 
  LOG_CRIT
• 
  LOG_ERR
• 
  LOG_WARNING
• 
  LOG_NOTICE
• 
  LOG_INFO
• 
  LOG_DEBUG

Python Bindings: Calling C or C++ From Python