Date Substraction


 
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# 1  
Question

In Unix script, how to get a "date - 1" ie, yesterday?
# 2  
Code:
#!/bin/bash

# figure out what yesterday was.
date '+%Y %m %d' |
 {
 read year month day

 day=`expr "$day" - 1`
 case "$day" in
 0)
 month=`expr "$month" - 1`
 case "$month" in
 0)
 month=12
 year=`expr "$year" - 1`
 ;;
 esac

 day=`cal $month $year | grep . | fmt -1 | tail -1`
 esac

 echo "Yeseterday was: $day $month $year"
                 }


Last edited by Yogesh Sawant; 05-20-2010 at 10:53 AM.. Reason: added code tags
# 3  
or if you are using GNU date, simply do:

Code:
date --date=yesterday


Last edited by Yogesh Sawant; 05-20-2010 at 10:52 AM.. Reason: added code tags
# 4  
MySQL Date Substraction

It works. Thank you.
# 5  
in Perl there is really handy way to manipulate Date
Code:
print scalar localtime (time() - 86400 * n);

it will substract n from current date and print the date

Code:
print scalar localtime (time() - 86400 * 1); #yesterday
print scalar localtime (time() - 86400 * 30); #Date of 30 days back

To get date four days from now
Code:
print scalar localtime (time() + 86400 * 4);

and so on....

Last edited by Yogesh Sawant; 05-20-2010 at 10:53 AM.. Reason: added code tags
 

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