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9

How do I get the current Unix time in milliseconds (i.e number of milliseconds since Unix epoch January 1 1970)?

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7 Answers

up vote 57 down vote accepted

This:

date +%s

will return the number of seconds since the epoch.

This:

date +%s%N

returns the seconds and current nanoseconds.

So:

date +%s%N | cut -b1-13

will give you the number of milliseconds since the epoch - current seconds plus the left three of the nanoseconds.

and from MikeyB - echo $(($(date +%s%N)/1000000)) (dividing by 1000 only brings to microseconds)

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9  
I wonder how many ms the cut adds :-) – Kyle Brandt♦ Jun 14 '10 at 16:23
you're looking at screen refresh time - that's already going to add something :) – warren Jun 14 '10 at 16:32
1  
I think seconds * 1000 will be fine :) – Richard Jun 14 '10 at 16:34
6  
Or if you want to do it all in the shell, avoiding the expensive overhead of an additional process (actually, we're avoiding the problem when the number of digits in %+s+N changes): echo $(($(date +%s%N)/1000)) – MikeyB Jun 14 '10 at 16:38
1  
It's the principle of the matter... avoid magic numbers and code what you actually mean. – MikeyB Jun 14 '10 at 18:02
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up vote 7 down vote

Unfortunately I only seem to be able to add new answers, not comment, but I think it's worth noting that the man asked for Unix, not Linux, and the current top answer (date +%s%N) doesn't work on my AIX system.

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3  
+1 Same for OS X, and FreeBSD – Slomojo May 19 '12 at 0:28
up vote 5 down vote

Just throwing this out there, but I think the correct formula with the division would be:

echo $(($(date +%s%N)/1000000))
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up vote 4 down vote

date +%N doesn't work on OS X, but you could use ruby -e 'puts Time.now.to_f' or python -c 'import time; print time.time()'.

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up vote 1 down vote

My solution is not the best but worked for me.

date +%s000

I just needed to convert a date like 2012-05-05 to milliseconds.

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up vote 1 down vote

If you are looking for a way to display the length of time your script ran, the following will provide a (not completely accurate) result:

As near the beginning of your script as you can, enter the following

basetime=$(date +%s%N)

This'll give you a starting value of something like 1361802943996000000

At the end of your script, use the following

echo "runtime: $(echo "scale=3;($(date +%s%N) - ${basetime})/(1*10^09)" | bc) seconds"

which will display something like

runtime: 12.383 seconds

Notes:

(1*10^09) can be replaced with 1000000000 if you wish

"scale=3" is a rather rare setting that coerces bc to do what you want. There are lots more!

I only tested this on Win7/MinGW... I don't have a proper *nix box to hand.

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up vote 0 down vote

Here is how to get time in milliseconds without performing division. Maybe it's faster...

# test=`date +%s%N`
# testnum=${#test}
# echo ${test:0:$testnum-6}
1297327781715
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Another alternative in pure bash that works only with bash 4.2+ is same as above but use printf to get the date. It will definitely be faster because no processes are forked off the main one. printf -v test '%(%s%N)T' -1 testnum=${#test} echo ${test:0:$testnum-6} Another catch here is that your strftime implementation should support %s and %N which is NOT the case on my test machine with bash 4.2. – akostadinov Sep 9 '11 at 9:36

protected by MadHatter Feb 25 at 14:49

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