Date manipulating

[Vasudevan MV]

Hi,

I have tried with "echo `TZ=IST+24 date`" to get previous day's date, but this doesn't work if the current time is (HH:MM) 00:00 to 05:00 AM, IST.
Can any one suggest me the better & simple command to get the previous day's date?.

Vasu

[Paula J Frazer-Campbell]

Hi

This is a nice script written by Tom Danzig which he posted some time ago.

HTH

Paula

[Robin Wakefield]

Hi Vasu,

If you have perl:

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

Rgds, Robin

[Vasudevan MV]

Hi Paula,

Thanks for your solution. But I am looking for single line command to get the previous day's date.

Vasu

[Santosh Nair_1]

Vasu,

I don't believe there is a one line solution for what you're asking. Espeically not in shell script. However, its quite easy in perl as Robin already pointed out...but not sure if Perl is an option for you.

-Santosh

[Robin Wakefield]

Hi Vasu,

If the perl solution is no good, we should find out why your original method is failing.

What's it show between 0:00 and 5:00? Can you output the IST timezone details in your /usr/lib/tztab. This *may* help...

Thanks, Robin.

[Santosh Nair_1]

Actually, I was just thinking about this. Your timezone should be IST-5:30. So in the proper string you should be using is
echo $(TZ=IST+18:30 date)

-Santosh

[Vasudevan MV]

Santosh,

I have tried that too "echo $(TZ=IST+18:30 date)"... but it should be generic.

Thanks
Vasu

[A. Clay Stephenson]

Hi Vasu:

I've had a script I've used for many years that converts calendar dates to Julian Days and back. Because I've seen so many requests for dates prior to today or 37 days from today, I've modified it with new args -p days for previous days or -n for next days. When suppiled with mm dd yyyy it converts to a Julian Day; when supplied with a Julian day it
outputs mm dd yyyy. No args and it converts today to a Julian Day.

This should work for you:
caljd.sh `caljd.sh -p 1`

The second calhd.sh takes today's date - 1 and converts it to a Julian Day which is in turn fed to the outer caljd.sh to output a mm dd yyyy.

To capture the output in a variable and get around the nested backquotes, try this:

PREV_DAY=$(caljd.sh `caljd.sh -p 1`)

If you are building file names and want to remove the spaces add the -s arg.

Regards, Clay