Shell Programming and Scripting

if [[ $PUB_FILES_PRESENT == "0" ]]
then 
echo "no"
else
echo "yes"
fi

if [[ "$PUB_FILES_PRESENT" = "0" ]]
then 
echo "no"
else
echo "yes"
fi

if [ $PUB_FILES_PRESENT -eq 0 ]                    #when you are comparing a variable
then 
echo "no"
else
echo "yes"
fi

directory="/ns/home/aash"
if [`ls "$directory"/*.PUB | wc -l 2>/dev/null` -eq 0 ]
then
echo no
else
echo yes
fi