Date Arimatic

The shell script uses perl to find the date 'n' days back

 #!/bin/ksh

# this script is used in date subtraction.
# the script uses perl command
# Similarly, the date before â??nâ?? days can be
# obtained by multiplying 86400 * n in the 
# place of 86400

Days=1

echo "
Yesterday's date...
"
a=`perl -e '$d = time();
   @f = localtime($d - 86400);
         printf "%04d %02d %02d
",$f[5]+1900, $f[4]+1, $f[3];
                                                   ' $Days`
echo $a

echo "
Two days back date...
"
b=`perl -e '$d = time();
   @f = localtime($d - 172800);
      printf "%04d %02d %02d
",$f[5]+1900, $f[4]+1, $f[3];
                                          ' $Days`
echo $b