Is there a way to get a Unix timestamp in Stata?

Question

This question was migrated from Cross Validated because it can be answered on Stack Overflow. Migrated 7 years ago.

I searched online and found several sources that talk about converting Unix timestamps to various workable formats, but none that allow me to actually get such a timestamp from within Stata. As of now, I use variations on

local curr_date = c(current_date)
local curr_time = c(current_time)

to apply timestamps to logs, data sets, etc. but I'd like to just use the Unix timestamp in seconds, if possible.

Answer 1

Are you familiar with help datetime? My understanding is that the Unix time stamp would be something like

display %12.0g clock("`c(current_date)' `c(current_time)'", "DMY hms" )/1000 - clock("1 Jan 1970", "DMY" )/1000

which of course you can use in other circumstances as well. (I am not a C programmer, I am a Stata user, but I do understand that it is easier for most people on this site to write a snippet of C code that would go into the guts of Stata than to RTFM... which is admirable in its own ways from where I sit, of course.)

Answer 2

One way to achieve this is to write a simple plugin. Compile this code, in a file called unixtimestamp.c

#include "stplugin.h"
#include <stdlib.h>
#include <time.h>
#include <stdio.h>

STDLL stata_call(int argc, char *argv[])
{
    time_t seconds;
    seconds = time(NULL);
    char buf[33];
    sprintf(buf, "%d", seconds);

    SF_display(buf);
    return(0);
}

with stplugin.h and stplugin.c in the same directory using this command (for a Linux system):

gcc -O3 -shared -DSYSTEM=OPUNIX -fPIC stplugin.c unix_timestamp.c -o unixtimestamp.plugin

The guide to creating plugins uses this command:

gcc -shared -DSYSTEM=OPUNIX stplugin.c unixtimestamp.c -o unixtimestamp.plugin

but on some systems, this gives an error instructing you to use the -fPIC flag, which is why I include it in my command. Also, optimizations aren't really necessary for such a simple plugin, but I included them regardless.

unixtimestamp.plugin should be placed in the ado/personal/ directory. Run Stata's sysdir function to find its location. On my system, it's HOME/ado/personal/ so I copied the plugin there. Then, from Stata, load the plugin:

program unixtimestamp, plugin

If no error message is displayed, run the plugin with:

plugin call unixtimestamp

As with any Stata command, you can also use a macro to simplify this if you plan to use this command frequently:

local unixtime plugin call unixtimestamp
`unixtime'

Answer 3

I use the following to grab a date/time stamp:

di "DateTime: $S_DATE $S_TIME"

Updated: You may use Unix shell commands directly inside Stata by prefixing them an exclamation mark. To echo Unix time try:

!date +%s
1344341160