CODEWITHSUNDEEP
macosshellunix
Oussama L.
Oussama L.

Reputation: 1912

Using SHELL BSD "date" command for conversion to Nanoseconds?

I need to convert a time to nanoseconds, the bsd date command isn't suitable, as the best it can returns are seconds.. date +"%H:%M:%S" returns 17:33:07..

Seems there is a difference between Mac's BSD date version, and the Linux GNU one. The last one can return nanoseconds. The first can't..

Should I be using python or ruby scripts instead of shell? Or is there another solution to get my nanoseconds on a Mac?

no in fact no %N

Upvotes: 1

Views: 1826

Answers (3)

Anya Shenanigans
Anya Shenanigans

Reputation: 94739

I differentiate code for the mac using a test for the presence of the --version option:

if ! date --version >/dev/null 2>&1; then # Mac
    micro=$(perl -e 'use Time::HiRes qw( gettimeofday ); my ($a, $b) = gettimeofday; print $b;')
else
    micro=$(($(date +%N) / 1000))
fi

The best accuracy for gettimeofday is microseconds, though.

Upvotes: 2

ghoti
ghoti

Reputation: 46856

The OSX date command doesn't do nanonseconds, but in OSX you can still get this from the system.

For example, in C, this should be the system uptime:

#include <inttypes.h>
#include <stdio.h>
#include <stdint.h>

#include <mach/mach_time.h>

int main(void)
{
        uint64_t t = mach_absolute_time();

        // Get ratio between mach_absolute_time units and nanoseconds.
        mach_timebase_info_data_t data;
        mach_timebase_info(&data);

        // Convert to nanoseconds.
        t *= data.numer;
        t /= data.denom;

        printf("%" PRIu64 "\n", t);

        return 0;
}

Save this to something like uptimens.c, then run make uptimens from your shell.

mac:~ ghoti$ ./uptimens
366181198555774
mac:~ ghoti$

Upvotes: 2

Zombo
Zombo

Reputation: 1

$ date +%T.%N
11:05:07.894987100

This gives you the current time with nanosecond accuracy.

Upvotes: -4

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