Shell Programming and Scripting

$DATE=1836
$[if [[ $DATE -ge 1700 ]] && [[ $DATE -le 2359 ]]]   ||   [if [[ $DATE -ge 0001 ]] && [[ $DATE -le 0900 ]]]; then
ksh: syntax error: `]]]' unexpected

 if [[ $DATE -ge 1700 ]] && [[ $DATE -le 2359 ]]

 if [[ $DATE -ge 0001 ]] && [[ $DATE -le 0900 ]]

if [ $DATE -ge 1700 -a $DATE -le 2359 -o $DATE -ge 0001 -a $DATE -le 0900 ]; then
 ....
fi

       condition1 -a condition2    True  if both condition1 and condition2 are
                   true. The -a binary primary is  left  asso-
                   ciative  and has higher precedence than the
                   -o binary primary.

       condition1 -o condition2    True if either condition1 or condition2  is
                   true.  The  -o binary primary is left asso-
                   ciative.