Shell Programming and Scripting

#! /bin/sh
year=`echo $1 | cut -c 1-4`
month=`echo $1 | cut -c 5,6`
day=`echo $1 | cut -c 7,8`
if [`echo "$1\c" | wc -c` -ne 8 ]
then
echo "Invalid date, please re-enter"
exit
elif [ $year -gt 0 -a $month -gt 0 -a $month -le 12 -a $day -gt 0 -a $day -le 31 ];then
echo $year $month $day
else
echo "Invalid date"
fi

ksh: $%#$:  not found
Invalid date, please re-enter
^C
[2] +  Done(127)               ./shellpgm36.sh %^&$%#$&
[1] +  Done                    ./shellpgm36.sh %^&$%#$&

if [ $# -ne 0 ]
then
dateval=`echo $1 | grep '^[0-9]\{8\}$'`
else
 echo "Invalid date,please re-enter in YYYYMMDD format"
 exit
fi

#! /bin/sh
#! /bin/sh

dateval=`date +%Y%m%d`
dateinput=$dateval
if [ $# -eq 0 ]
then
dateval=`date +%Y%m%d`
echo $dateval
exit
fi
if [ $# -ne 0 ]
then
dateval=`echo $1 | grep '^[0-9]\{8\}$'`
if [ $? -ne 0 ]
then
 echo "Invalid date,please re-enter in YYYYMMDD format"
 exit
fi
fi

dateval=`echo $1 | grep "^[0-9]\{8\}$"`

echo $1 | grep "^[0-9]\{8\}" > /dev/null