Date operations in Unix?

Shell Programming and Scripting
1

Hi Friends,

I need help in below requirements,

  1. I have to get current datetime + <mins> into a variable
  2. I have to compage dates like,
    A=01-JAN-2009 10:20:10
    B=01-JAN-2009 10:30:00

C=<same format date as above>
I have to find whether,

  1. C is less than A OR,
  2. C is greater than B OR,
  3. C is in between A and B.

Please help me in this.

Thanks,
Raja.

2

TRy Perderabo's datecalc script:
http://www.unix.com/answers-frequently-asked-questions/13785-yesterdays-date-date-arithmetic.html

Convert A to epoch seconds (%s), then B to epoch seconds (%s), C to epoch seconds.
You now have three numbers to compare to answer your questions.

3

Try this: In my example below, it is assuming B is always greater than A. This could be coded to where it doesn't matter as well.

#!/bin/ksh

DATE_A=$(date +%Y%m%d%H%M%S -d "$1")
DATE_B=$(date +%Y%m%d%H%M%S -d "$2")

DATE_C=$(date +%Y%m%d%H%M%S)

if [ "${DATE_C}" -gt "${DATE_B}" ]; then
   echo "C, ${DATE_C},  is greater than B, ${DATE_B}"
elif [ "${DATE_C}" -gt "${DATE_A}" ]; then
   echo "DATE_C, ${DATE_C},  is between A, ${DATE_A}, and B, ${DATE_B}"
else
   echo "C, ${DATE_C},  is less than A, ${DATE_A}"
fi

tests

$./chk_date.ksh "01-JAN-2009 10:20:10" "12-DEC-2009 10:30:00"
C, 20091125051733,  is between A, 20090101102010, and B, 20091212103000

$ ./chk_date.ksh "01-DEC-2009 10:20:10" "12-DEC-2009 10:30:00"
C, 20091125051752,  is less than A, 20091201102010

$ ./chk_date.ksh "01-JAN-2009 10:20:10" "01-JAN-2009 10:30:00"
C, 20091125051824,  is greater than B, 20090101103000
4

This is working fine..
Thank you friend!

For date B, I need to add some mins with current date. How could i get it?

---------- Post updated at 10:36 PM ---------- Previous update was at 10:34 PM ----------

I have seen epoch seconds method in net, It is using perl command.
I do not have perl in my system. Thanks for your quick response friend :slight_smile:

5

Can you explain what you mean by needing to add some minutes with current date?

6

I have to do comparison between two date values. One is current date time (min) and another date (max) will be calculated by adding some input minutes with current date time.

7

Pls help to get the above requirement.
Ex:
Min_Date=Current Datetime (Format: DD-MON-YYYY HH24:MI:SS)
Max_Date=Current Datetime + X mins (Format: DD-MON-YYYY HH24:MI:SS)

8

Check out the link provided by Jim McNamara above. It contains links to other solutions as well. If none of these work for you, let me know and I can dig up a function I wrote to do this. That was several jobs ago though and I'm not sure where I have it.