In a unix shell, how to get yesterday's date into a variable?

Question

I\'ve got a shell script which does the following to store the current day\'s date in a variable \'dt\':

date \"+%a %d/%m/%Y\" | read dt
echo ${dt}


        

Answer 1

Thanks for the help everyone, but since i'm on HP-UX (after all: the more you pay, the less features you get...) i've had to resort to perl:

perl -e '@T=localtime(time-86400);printf("%02d/%02d/%04d",$T[3],$T[4]+1,$T[5]+1900)' | read dt

Answer 2

You have atleast 2 options

1. Use perl:

   perl -e '@T=localtime(time-86400);printf("%02d/%02d/%02d",$T[4]+1,$T[3],$T[5]+1900)'
   

2. Install GNU date (it's in the sh_utils package if I remember correctly)

   date --date yesterday "+%a %d/%m/%Y" | read dt
   echo ${dt}
   

3. Not sure if this works, but you might be able to use a negative timezone. If you use a timezone that's 24 hours before your current timezone than you can simply use date.

Answer 3

For Hp-UX only below command worked for me:

TZ=aaa24 date +%Y%m%d

you can use it as :

ydate=`TZ=aaa24 date +%Y%m%d`

echo $ydate

Answer 4

You can use GNU date command as shown below

Getting Date In the Past

To get yesterday and earlier day in the past use string day ago:

date --date='yesterday'

date --date='1 day ago'

date --date='10 day ago'

date --date='10 week ago'

date --date='10 month ago'

date --date='10 year ago'

Getting Date In the Future

To get tomorrow and day after tomorrow (tomorrow+N) use day word to get date in the future as follows:

date --date='tomorrow'

date --date='1 day'

date --date='10 day'

date --date='10 week'

date --date='10 month'

date --date='10 year'

Answer 5

I have shell script in Linux and following code worked for me:

#!/bin/bash
yesterday=`TZ=EST+24 date +%Y%m%d` # Yesterday is a variable
mkdir $yesterday # creates a directory with  YYYYMMDD format

Answer 6

If you are on a Mac or BSD or something else without the --date option, you can use:

date -r `expr \`date +%s\` - 86400` '+%a %d/%m/%Y'

Update: or perhaps...

date -r $((`date +%s` - 86400)) '+%a %d/%m/%Y'