UNIX for Dummies Questions & Answers

Hello All,
I am a newbie to unix shell scripting and need to write a script that displays the difference between two variables that stores date value.

For example,

Code:

F1=`ls -ltr file1* | tail -1 |tr -s ' ' |cut -d' ' -f6,7,8`
F2=`ls -ltr file2* | tail -1 |tr -s ' ' |cut -d' ' -f6,7,8`

F1 and F2 stores the values like Aug 02 06:54(month,date and time). I need to find the difference between these two variables. I tried using expr and just regular subtraction which doesnt work. Can you please help me understand how to do date arithmetic in unix?

I tried searching and found some stuff like date -d option which doesnt work in my case.

Please share your valuable suggestions.

Thanks,
Priya.

Take a look at this: Link

Thanks for the link. I did look into that link before, but it calculates only date difference. I need to find both date and time difference. Can you please advice how to convert the date I get using ls command into generic format? Aug 02 11:23 into 20130802 11:23

Hi.
See:

Code:

NAME
       ddiff - manual page for ddiff 0.2.3

SYNOPSIS
       ddiff [OPTION]... DATE/TIME [DATE/TIME]...

DESCRIPTION
       ddiff 0.2.3

       Compute duration from DATE/TIME (the reference date/time) to the other
       DATE/TIMEs given and print the result as duration. 
...

This is part of https://github.com/hroptatyr/dateutils -- the source can be downloaded as a zip file. Some GNU/Linux distributions also have it packaged up, e.g. Debian jessie

A sample calculation from man ddiff:

Code:

         % ddiff 2012-03-01T12:17:00 2012-03-02T14:00:00
         92580s

Best wishes ... cheers, drl