How to compare null and space using single if condition

Hi

I have a input file with many fields and each filed will be with in double quotes(""). i want to check fields contains balnk,null or space using condition using if. when i write code as below for if condition its not working

a=`awk -F ',' '{gsub("\"", "", $1);'NF==0';printf $1}' temp.txt`
echo $a

if [ -z "$a" ] || ["$a" = " " ]
then
echo "1st filed contains null or space please correct"
else
echo " field has data"
fi

Error message:

Account_SourceFile_Validation.sh[288]: [ : not found.

Can any one help on this.

Thanks

Try this:

awk -F "," '
{s=$0;gsub(" ", "")}
/""/{print "With blanc field: "s;next}1' temp.txt

Regards

Or just simply

egrep '(^|,)" *"(,|$)|^,|,,|,$' temp.txt

If there are fields which contains commas inside the double quotes, you need to elaborate on this (but it's not hideously complex then, either).

Thank you very much.It was a timely help.