How can I generate Unix timestamps?

问题:

Related question is "Datetime To Unix timestamp", but this question is more general.

I need Unix timestamps to solve my last question. My interests are Python, Ruby and Haskell, but other approaches are welcome.

What is the easiest way to generate Unix timestamps?

回答1:

In Linux or MacOS you can use:

date +%s

where

• +%s, seconds since 1970-01-01 00:00:00 UTC. (GNU Coreutils 8.24 Date manual)

Example output now 1454000043.

回答2:

in Ruby:

>> Time.now.to_i
=> 1248933648

回答3:

In python add the following lines to get a time stamp:

>>> import time
>>> time.time()
1335906993.995389
>>> int(time.time())
1335906993

回答4:

curl icanhazepoch.com

Basically it's unix timestamps as a service (UTaaS)

回答5:

In Perl:

>> time
=> 1335552733

回答6:

The unix 'date' command is surprisingly versatile.

date -j -f "%a %b %d %T %Z %Y" "`date`" "+%s"

Takes the output of date, which will be in the format defined by -f, and then prints it out (-j says don't attempt to set the date) in the form +%s, seconds since epoch.

回答7:

First of all, the Unix 'epoch' or zero-time is 1970-01-01 00:00:00Z (meaning midnight of 1st January 1970 in the Zulu or GMT or UTC time zone). A Unix time stamp is the number of seconds since that time - not accounting for leap seconds.

Generating the current time in Perl is rather easy:

perl -e 'print time, "\n"'

Generating the time corresponding to a given date/time value is rather less easy. Logically, you use the strptime() function from POSIX. However, the Perl POSIX::strptime module (which is separate from the POSIX module) has the signature:

($sec, $min, $hour, $mday, $mon, $year, $wday, $yday) = 
                                     POSIX::strptime("string", "Format");

The function mktime in the POSIX module has the signature:

mktime(sec, min, hour, mday, mon, year, wday = 0, yday = 0, isdst = 0)

So, if you know the format of your data, you could write a variant on:

perl -MPOSIX -MPOSIX::strptime -e \
    'print mktime(POSIX::strptime("2009-07-30 04:30", "%Y-%m-%d %H:%M")), "\n"'

回答8:

$ date +%s.%N

where (GNU Coreutils 8.24 Date manual)

• +%s, seconds since 1970-01-01 00:00:00 UTC
• +%N, nanoseconds (000000000..999999999) since epoch

Example output now 1454000043.704350695. I noticed that BSD manual of date did not include precise explanation about the flag +%s.

回答9:

For completeness, PHP:

php -r 'echo time();'

In BASH:

clitime=$(php -r 'echo time();')
echo $clitime

回答10:

In Haskell...

To get it back as a POSIXTime type:

import Data.Time.Clock.POSIX
getPOSIXTime

As an integer:

import Data.Time.Clock.POSIX
round `fmap` getPOSIXTime

回答11:

public static Int32 GetTimeStamp()
    {
        try
        {
            Int32 unixTimeStamp;
            DateTime currentTime = DateTime.Now;
            DateTime zuluTime = currentTime.ToUniversalTime();
            DateTime unixEpoch = new DateTime(1970, 1, 1);
            unixTimeStamp = (Int32)(zuluTime.Subtract(unixEpoch)).TotalSeconds;
            return unixTimeStamp;
        }
        catch (Exception ex)
        {
            Debug.WriteLine(ex);
            return 0;
        }
    }

回答12:

in Haskell

import Data.Time.Clock.POSIX

main :: IO ()
main = print . floor =<< getPOSIXTime

in Go

import "time"
t := time.Unix()

in C

time(); // in time.h POSIX

// for Windows time.h
#define UNIXTIME(result)   time_t localtime; time(&localtime); struct tm* utctime = gmtime(&localtime); result = mktime(utctime);

in Swift

NSDate().timeIntervalSince1970 // or Date().timeIntervalSince1970

回答13:

With NodeJS, just open a terminal and type:
node -e "console.log(new Date().getTime())" or node -e "console.log(Date.now())"

回答14:

Let's try JavaScript:

var t = Math.floor((new Date().getTime()) / 1000);

...or even nicer, the static approach:

var t = Math.floor(Date.now() / 1000);

In both cases I divide by 1000 to go from seconds to millis and I use Math.floor to only represent whole seconds that have passed (vs. rounding, which might round up to a whole second that hasn't passed yet).

回答15:

If you need a Unix timestamp from a shell script (Bourne family: sh, ksh, bash, zsh, ...), this should work on any Unix machine as unlike the other suggestions (perl, haskell, ruby, python, GNU date), it is based on a POSIX standard command and feature.

PATH=`getconf PATH` awk 'BEGIN {srand();print srand()}'