UNIX for Advanced & Expert Users

I came up with a potential solution to find the previous Saturday's date based on current system date.

I made use of the existing logic to find previous day (posted on this forum) and based on the current day of the week, I keep looping and calling the previous_day() function until I get to previous Saturday's date.

Please let me know if you find any flaws with my script.

Thanks.

Code follows:

==========================================================
#!/usr/bin/ksh
#
####################################################
# Script to find previous Saturday's date based on current system date
####################################################

# Initialize variable
i=0

#
# Function area - copied from forum posting
#
previous_day()
{
# Convert variables into numeric fields
YEAR=`expr "$YEAR" + 0`
MONTH=`expr "$MONTH" + 0`
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

# If DAY less than 10, append zero in front
if [ ${DAY} -lt 10 ]
then
DAY=0${DAY}
fi

# If MONTH less than 10, append zero in front
if [ ${MONTH} -lt 10 ]
then
MONTH=0${MONTH}
fi

} # End of previous_day() function


# Obtain current system date
YEAR=`date '+%Y'`
MONTH=`date '+%m'`
DAY=`date '+%d'`

# Find current day of the week
wkday=`date '+%w'`
wkday=`expr "$wkday" + 1`

# Loop and call function previous_day until we get previous Saturday's date
while [ i -lt ${wkday} ]
do
# Call function to find previous day
previous_day

let i=i+1
done


# Return yesterday date
echo "$YEAR$MONTH$DAY"