Shell Programming and Scripting

#!/bin/sh

month=`date +%m`
year=`date +%Y`
echo $month
a=02

# Retaining Data for Current and Previous Month
lmonth=`expr $month - $a`
  if test "$lmonth" = "0"
   then
    lmonth=12
  year=`expr $year - 1`
  fi
echo $year
echo $lmonth

04
2012
2

04
2012
02

#!/bin/sh

month="`date +%m`"
year="`date +%Y`"
printf "%02d\n" ${month}

# Retaining Data for Current and Previous Month
case "${month}" in
        "01")   lmonth=11
                year=`expr ${year} - 1`
                ;;
        "02")   lmonth=12
                year=`expr ${year} - 1`
                ;;
        *)      lmonth=`expr ${month} - 2`
                ;;
esac
#
printf "%04d\n" ${year}
printf "%02d\n" ${lmonth}