Command to get time in milliseconds

Question

Is there a shell command in Linux to get the time in milliseconds?

Answer 1

date command didnt provide milli seconds on OS X, so used an alias from python

millis(){  python -c "import time; print(int(time.time()*1000))"; }

OR

alias millis='python -c "import time; print(int(time.time()*1000))"'

---

EDIT: following the comment from @CharlesDuffy. Forking any child process takes extra time.

$ time date +%s%N
1597103627N
date +%s%N  0.00s user 0.00s system 63% cpu 0.006 total

Python is still improving it's VM start time, and it is not as fast as ahead-of-time compiled code (such as date).

On my machine, it took about 30ms - 60ms (that is 5x-10x of 6ms taken by date)

$ time python -c "import time; print(int(time.time()*1000))"
1597103899460
python -c "import time; print(int(time.time()*1000))"  0.03s user 0.01s system 83% cpu 0.053 total

I figured awk is lightweight than python, so awk takes in the range of 6ms to 12ms (i.e. 1x to 2x of date):

$ time awk '@load "time"; BEGIN{print int(1000 * gettimeofday())}'
1597103729525
awk '@load "time"; BEGIN{print int(1000 * gettimeofday())}'  0.00s user 0.00s system 74% cpu 0.010 total

Answer 2

Here is a somehow portable hack for Linux for getting time in milliseconds:

#!/bin/sh
read up rest </proc/uptime; t1="${up%.*}${up#*.}"
sleep 3    # your command
read up rest </proc/uptime; t2="${up%.*}${up#*.}"

millisec=$(( 10*(t2-t1) ))
echo $millisec

The output is:

3010

This is a very cheap operation, which works with shell internals and procfs.

Answer 3

date +%s%N returns the number of seconds + current nanoseconds.

Therefore, echo $(($(date +%s%N)/1000000)) is what you need.

Example:

$ echo $(($(date +%s%N)/1000000))
1535546718115

date +%s returns the number of seconds since the epoch, if that's useful.

Answer 4

Nano is 10⁻⁹ and milli 10⁻³. Hence, we can use the three first characters of nanoseconds to get the milliseconds:

date +%s%3N

From man date:

%N nanoseconds (000000000..999999999)

%s seconds since 1970-01-01 00:00:00 UTC

Source: Server Fault's How do I get the current Unix time in milliseconds in Bash?.

Answer 5

Perl can be used for this, even on exotic platforms like AIX. Example:

#!/usr/bin/perl -w

use strict;
use Time::HiRes qw(gettimeofday);

my ($t_sec, $usec) = gettimeofday ();
my $msec= int ($usec/1000);

my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) =
    localtime ($t_sec);

printf "%04d-%02d-%02d %02d:%02d:%02d %03d\n",
    1900+$year, 1+$mon, $mday, $hour, $min, $sec, $msec;

Answer 6

• date +"%T.%N" returns the current time with nanoseconds.

  06:46:41.431857000
  

• date +"%T.%6N" returns the current time with nanoseconds rounded to the first 6 digits, which is microseconds.

  06:47:07.183172
  

• date +"%T.%3N" returns the current time with nanoseconds rounded to the first 3 digits, which is milliseconds.

  06:47:42.773
  

In general, every field of the date command's format can be given an optional field width.