date minus some number

[Sid Shapiro]

how to substract some number (let say 2 ) from currect date and get the date of 2 days back.

let say today is 05/02/01
substract = 2

should show me 30 (ie 30th,april)

[Carsten Krege]

You could do it with adb if you know how to express the current date in seconds since 1970 (should be possible to get with a short C program that uses gettimeofday() ).

# echo "0d919818576=Y" | adb
1999 Feb 24 02:09:36

Here 919818576 is the number of seconds since 1970 on Feb 24 1999.

If you want to get the day before, let adb subtract 86400 seconds (=1 day):

# echo "0d919818576-0d86400=Y" |adb
1999 Feb 23 02:09:36

Putting this into a small script that, shouldn't be hard, e.g. to get the number of seconds for in four days is simply:

# echo "4 * 86400" |bc
345600

Probably there is also an easier way to do this.

Carsten

[Tom Danzig]

I wrote a script a while back to do this (attached). It will give you the date any given number of days ago (within reason).

[Juan González]

Hi Tom,
to complete what Carsten do:

Put in a file (minus.c)
#include
#include

int main(argc, argv)
int argc;
char *argv[];
{
struct timeval time;
if (argc!=2) {
printf("Error\n");
exit(0);
}
gettimeofday(&time,NULL);
printf("0d%d=Y",time.tv_sec - atoi(argv[1])*86400);
}

Compile it:
#cc minus.c -o minus

And then (if you want to know the date 2 days ago)
#echo `./minus 2`|adb

Best regards

[Mladen Despic]

Tom,

The attached script does the job by using 'cal' to quickly determine the number of days in the previous month.
You can probably make it shorter, especially if you do not require a particular date format in the output.

Mladen

[Sid Shapiro]

thanx Juan Gonz?lez . your script script seems to be small and easy to implement .

[Ralph Grothe]

Here's a Perl oneliner:

perl -e 'print scalar localtime(time-2*86400),"\n"'

If you need fancier formatting check the list entries returned from localtime in an array/list l-value context:

perldoc -f localtime

or

perldoc perlfunc

[Davide Depaoli]

Try the attached script. This script come back 1 day (yesterday), but you may customize it for your porpouse.

Hope this helps
regards Davide