Converting 'date' to Epoch

[Joel Shank]

Can anyone tell me how to convert a standard UNIX date to a timestamp (seconds from Epoch).

I know I can use time() to get the current Epoch, but I want to compute Epoch for ANY entered date.

Thanks for your assistance,
jls

[S.K. Chan]

Check this..
http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x3d9b03bbece8d5118ff40090279cd0f9,00.html

[Joel Shank]

Thanks, but that was my question on converting Epoch to a date/time. Now what I need is the reverse, take any date-format and convert it to Epoch.

[Robin Wakefield · Accepted solution]

Hi Joel,

This is one way of doing it, using perl & local timezones:

============================================
#!/opt/perl5/bin/perl

use Time::Local;
my %months=qw(Jan 0 Feb 1 Mar 2 Apr 3 May 4 Jun 5 Jul 6 Aug 7 Sep 8 Oct 9 Nov 10 Dec 11);
my %days=qw(Sun 0 Mon 1 Tue 2 Wed 3 Thu 4 Fri 5 Sat 6);

my ($hour,$min,$sec)=split ':',$ARGV[3];
my $day=$days{$ARGV[0]};
my $month=$months{$ARGV[1]};
my $mday=$ARGV[2];
my $year=$ARGV[4]-1900;

my $time=timelocal($sec,$min,$hour,$mday,$month,$year);
print "$time\n";
===========================================

So, to run it, you'd use:

./date2epoch.pl Thu Feb 28 16:09:55 2002
1014912595

Rgds, Robin.

[Joel Shank]

Thank you Robin.

That will work. Do you know how I can do this in C? I'd really like to make this more portable.

jls

[Robin Wakefield]

Hi Joel,

Here goes:

====================================
/*

Convert date to epoch time

*/

#include
#include
#include
#include
#include

#define FALSE 0
#define TRUE 1

int main(argc,argv)
int argc;
char *argv[];

{
struct tm *dateptr;
time_t date;
int do_exit=FALSE;

if (argc != 2) {
fprintf(stderr, "Usage: %s \n", argv[0]);
exit(1);
}


/* Convert date */
dateptr = getdate(argv[1]);
if (getdate_err != 0) {
fprintf(stderr, "%s: Could not interpret %s. Error = %d\n", argv[0], argv[1], getdate_err);
exit(1);
}

date = mktime(dateptr);
if (date == -1) {
fprintf(stderr, "Could not \"mktime\" for date, errno=%d\n", errno);
exit(1);
}

printf("%d\n", date);

exit(0);
}
========================================

Now create a file containing "%c", say, /tmp/datemsk

and then:

export DATEMSK=/tmp/datemsk

Compile your program, then run it:

# ./a.out "`date "+%c"`"
1014914858

the file contains the date format that you wish to use (man getdate).

Rgds, Robin.

[Joel Shank]

Robin:

Thank you so much. This is EXACTLY what I was looking for!

jls