How can I generate Unix timestamps?

Question

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?

Answer 1

In Perl:

>> time
=> 1335552733

Answer 2

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

Answer 3

$ 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.

Answer 4

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.

Answer 5

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.

Answer 6

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).