What is a UNIX timestamp?

What is a UNIX timestamp ( UNIX Timestamp)?

UNIX timestamp, or Unix time or POSIX time, is a time representation, it is defined as the total number of seconds from GMT, January 1, January 01, 1970 to the present. UNIX timestamps are used not only in UNIX and Unix-like systems, but also in many other operating systems.

Currently, a considerable number of operating systems use 32-bit binary numbers to represent the time. The UNIX timestamp of such systems can be used up to GMT, January 1, January 19, 2038 (Binary:01111111 11111111 11111111 11111111). In the next second, the binary number will change10000000 00000000 00000000 00000000An overflow error occurs, causing the system to misunderstand the time as December 13, 1901. This may cause software faults or even system paralysis. Systems that use 64-bit binary numbers to represent time (a maximum of 292,277,026,596 seconds from January 1, December 04 to GMT) will not experience such overflow issues.

How to obtain the current UNIX timestamp in different programming languages ( UNIX Timestamp)?

Java	Time
Javascript	Math. Round (new date (). gettime ()/1000) The unit of the value returned by gettime () is millisecond.
Microsoft. NET/C #	Epoch = (datetime. Now. touniversaltime (). ticks-621355968000000000)/10000000
MySQL	Select unix_timestamp (now ())
Perl	Time
PHP	Time ()
PostgreSQL	Select extract (epoch from now ())
Python	Import time first and then time. Time ()
Ruby	Obtain UNIX timestamp: time. Now or time. New Display UNIX timestamp: time. Now. to_ I
SQL Server	Select datediff (S, '2017-01-01 00:00:00 ', getutcdate ())
Unix/Linux	Date + % s
VBScript/asp	Datediff ("S", "01/01/1970 00:00:00", now ())
Other operating systems (If Perl is installed in the System)	Command Line status: Perl-e "Print time"

How to Implement UNIX timestamps in different programming languages ( UNIX Timestamp) → Normal time?

Java	String date = new java. Text. simpledateformat ("DD/MM/YYYY hh: mm: SS"). Format (New java. util. Date (UNIX timestamp * 1000 ))
Javascript	First var unixtimestamp = new date (UNIX timestamp * 1000) and then commontime = unixtimestamp. tolocalestring ()
Linux	Date-d @ UNIX Timestamp
MySQL	From_unixtime (UNIX timestamp)
Perl	First my $ time = UNIX Timestamp and then my ($ sec, $ min, $ hour, $ day, $ month, $ year) = (localtime ($ time) [0, 1, 2, 3, 4, 5, 6]
PHP	Date ('R', Unix timestamp)
PostgreSQL	Select timestamp with Time Zone 'epoch' + UNIX timestamp) * interval '1 second ';
Python	Import time first and then time. gmtime (UNIX timestamp)
Ruby	Time. At (UNIX timestamp)
SQL Server	Dateadd (S, Unix timestamp, '2017-01-01 00:00:00 ')
VBScript/asp	Dateadd ("S", Unix timestamp, "01/01/1970 00:00:00 ")
Other operating systems (If Perl is installed in the System)	Command Line status: Perl-e "Print scalar (localtime (UNIX timestamp ))"

How to implement common time → UNIX timestamp in different programming languages ( UNIX Timestamp)?

Java	Long epoch = new java. Text. simpledateformat ("DD/MM/YYYY hh: mm: SS"). parse ("01/01/1970 01:00:00 ");
Javascript	VaR commontime = new date (date. UTC (year, month-1, day, hour, minute, second ))
MySQL	Select unix_timestamp (time) Time Format: YYYY-MM-DD hh: mm: SS or yymmdd or yyyymmdd
Perl	Use Time: local first and then my $ time = timelocal ($ sec, $ min, $ hour, $ day, $ month, $ year );
PHP	Mktime (hour, minute, second, day, month, year)
PostgreSQL	Select extract (epoch from date ('yyyy-MM-DD hh: mm: ss '));
Python	First import time and then int (time. mktime (time. strptime ('yyyy-MM-DD hh: mm: ss', '% Y-% m-% d % H: % m: % s ')))
Ruby	Time. Local (year, month, day, hour, minute, second)
SQL Server	Select datediff (S, '2017-01-01 00:00:00 ', time)
Unix/Linux	Date + % s-d "Jan 1, 1970 00:00:01"
VBScript/asp	Datediff ("S", "01/01/1970 00:00:00", time)

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