Emergency UNIX and Linux Support

date '+%m %d %Y' |  
{  
read MONTH DAY YEAR 
DAY=`expr "$DAY" - 1`  
case "$DAY" in  
        0)  
           MONTH=`expr "$MONTH" - 1`  
                case "$MONTH" in  
                        0)  
                           MONTH=12  
                           YEAR=`expr "$YEAR" - 1`  
                        ;;  
                esac  
        DAY=`cal $MONTH $YEAR | grep . | fmt -1 | tail -1`  
esac  
echo "$MONTH$DAY$YEAR"  
}

yest=`yest.sh`
echo $yest

# sh somescript.sh
08192010

....
echo "$MONTH$DAY$YEAR"

info date

date -d yesterday
date --date=yesterday
date -d '1 day ago'