How do I get the current Unix time in milliseconds in Bash?

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)

You may simply use %3N to truncate the nanoseconds to the 3 most significant digits (which then are milliseconds):

$ date +%s%3N
1397392146866

This works e.g. on my Kubuntu 12.04 (Precise Pangolin).

But be aware that %N may not be implemented depending on your target system. E.g. tested on an embedded system (buildroot rootfs, compiled using a non-HF ARM cross toolchain) there was no %N:

$ date +%s%3N
1397392146%3N

(And also my (non rooted) Android tablet doesn't have %N.)

date +%N doesn't work on OS X, but you could use one of

• Ruby: ruby -e 'puts Time.now.to_f'
• Python: python -c 'import time; print(int(time.time() * 1000))'
• Node.js: node -e 'console.log(Date.now())'
• PHP: php -r 'echo microtime(TRUE);'
• Elixir: DateTime.utc_now() |> DateTime.to_unix(:millisecond)
• The Internet: wget -qO- http://www.timeapi.org/utc/now?\\s.\\N
• or for milliseconds rounded to nearest second date +%s000

My solution is not the best, but it worked for me:

date +%s000

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

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

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

This solution works on macOS.

If you consider using a Bash script and have Python available, you could use this code:

#!/bin/bash

python -c 'from time import time; print int(round(time() * 1000))'

For the people that suggest running external programs to get the milliseconds... at that rate, you might as well do this:

wget -qO- http://www.timeapi.org/utc/now?\\s.\\N

Point being: before picking any answer from here, please keep in mind that not all programs will run under one whole second. Measure!

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 Windows 7/MinGW... I don't have a proper *nix box at hand.

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

Update: Another alternative in pure Bash that works only with Bash 4.2+ is the 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 though is that your strftime implementation should support %s and %N which is not the case on my test machine. See man strftime for supported options. Also see man bash to see printf syntax. -1 and -2 are special values for time.

Another solution for MacOS: GNU Coreutils

I have noticed that the MacOS' version of the date command is not interpreting the %N format sequence as nanoseconds but simply prints N to the output when I started using my .bashrc script from Linux, that's using it to measure how long executed commands run, on a MacOS machine.

After a little bit of research, I have learned that only the GNU date from the GNU Coreutils package does support milliseconds. Fortunately, it's pretty easy to install it on MacOS using Homebrew:

brew install coreutils

Since that package contains executables that are already present on MacOS, Coreutils' executables will be installed with a g prefix, so date will be available as gdate.

See for example this page for further details.