How do I subtract 1 day from date

[Helen Herring]

I have a script with:

Day = 'date +%a'

dumpfile="holdfile_${Day}.dmp.Z

I need to subract 1 day from the date.
Can you

[linuxfan]

Hi Kathy,

You could do something as simple as

YESTERDAY=`TZ=PST+24 date +%D`
or in perl
yesterday=$(perl -e 'print scalar localtime(time-1*86400),"\n"' | cut -c 5-11)

If you want more, just do a search in the forums, you will get quite a few options

-Regards
Ramesh

[linuxfan]

Hi Kathy,

My mistake, you are using
Day = `date +%a`

which gives the day of the week, so you may have to use
yest=`TZ=PST+24 date +%a`

-HTH
Ramesh

[Joseph C. Denman]

For something like keeping track of dumps and this like that, I have found it easier to user julian date.

DAY=`date +%j`
YESTERDAY=`expr $DAY - 1`

...jcd...

[Helen Herring]

I want to use the day of the week. Can the -1 be used with day if day has been set to the day of the week?

[Joseph C. Denman]

Sure, the only problem will be Monday which is 1. However, you can fix that:

DAY=`date +%u` #DAYS of week mon-sun 1-7
if [ $DAY -eq 1 ]
then
YESTERDAY=7
else
YESTERDAY=`expr $DAY - 1`
fi

...jcd...

[Jeffrey S. Sims]

If you have perl running on your system try using this command:

perl -e 'print scalar localtime(time-1*86400),"\n"'

And yes this works with text dates

[Sridhar Bhaskarla]

Kathy,

I will prepare a table like this


MON=1
TUES=2
WED=3
THU=4
FRI=5
SAT=6
SUN=7

NOW you can use the same trick as told by Joseph.

DAY=`date +%u`
if [ $DAY -eq 1 ]
then
YESTERDAY=7
else
YESTERDAY=`expr $DAY - 1`
YESTERDAY_IS=`grep YESTERDAY table |awk '{FS=
"=";print $1}`
fi

You can use YESTERDAY_IS in your program to replace the day of the week.

-Sri

[Sridhar Bhaskarla]

Kathy,

I will prepare a table like this


MON=1
TUES=2
WED=3
THU=4
FRI=5
SAT=6
SUN=7

NOW you can use the same trick as told by Joseph.

DAY=`date +%u`
if [ $DAY -eq 1 ]
then
YESTERDAY=7
else
YESTERDAY=`expr $DAY - 1`
YESTERDAY_IS=`grep $YESTERDAY table |awk '{FS=
"=";print $1}`
fi

You can use YESTERDAY_IS in your program to replace the day of the week.

-Sri

[Paula J Frazer-Campbell]

Hi

Here is a nice script written by Tom Danzig that will work back to 01/01/01.

usage is :- datwhen -n

HTH

Paula

[Paula J Frazer-Campbell]

ps

to clarify the datewhen bit :- that is what I called the script on my server.

Paula