I am running a program where in I have this command
which is giving error the shift: number is not correct.
can you please tell me how shift actually works?

the line which is giving error is-
set $PARAM; shift; shift; shift; shift; shift; shift; shift; shift

Is it related somewhere to these parameters which is set before this line
PARAM=$*

case "$1" in
"-h"|"-H")
give_help
exit -1
;;
"-p"|"-P")
give_params
exit -1
;;
esac

eval REQID=`echo $PARAM | awk ' { split($2, var, "=")
printf("%s", var[2]) }'`
eval LOGIN=`echo $PARAM | awk ' { split($3, var, "=")
printf("%s", var[2]) }'`
eval USRID=`echo $PARAM | awk ' { split($4, var, "=")
printf("%s",var[2]) }'`
eval USRNM=`echo $PARAM | awk ' { split($5, var, "=")
printf("%s", var[2]) }'`
eval PRINT=`echo $PARAM | awk ' { split($6, var, "=")
printf("%s", var[2]) }'`
eval SVOUT=`echo $PARAM | awk ' { split($7, var, "=")
printf("%s", var[2]) }'`
eval COPNO=`echo $PARAM | awk ' { split($8, var, "=")
printf("%s", var[2]) }'`

export PARAM \
REQID \
LOGIN \
USRID \
USRNM \
PRINT \
SVOUT \
COPNO

If the number of shift commands is more than the number of parameters to your script then you will get the error shift: number is not correct.

I think you dont need set and shift commands.