Shell Programming and Scripting

Hi all,
My input file having the following details,

Code:

sid,worldpar0334,1024,production setup

am storing all values like this

Code:

C1=cut -d "," -f1
C2=cut -d "," -f2
C3=cut -d "," -f3
C4=cut -d "," -f4

so now in above case we have all values, but

if my input file is like this
sid,worldpar0334,,production setup

I ll store the data as above but now C3 doesn't have a value. While testing like this

Code:

if [ -z ${C3} ] ; then
  echo null
fi

while executing am getting a following error in the console,

test.sh[814]: test: 0403-004 Specify a parameter with this command

Even i tried,

Code:

if [ ${C3} = "" ] ; then
  echo null
fi

Kindly let me know how can I test if the value is null in above scenario...

Thanks

Gopal

Quote the variable:

Code:

if [ -z "${C3}" ] ; then
  echo null
fi