Shell Programming and Scripting

Hi
I have 4 variables W, X, Y & Z where I read from env for a user. I am trying to check for the value of each, and if any is empty, I want to ask the user to enter it via script. How do I do that?

Hi,

what script language would you use?

I use Bourne shell script.

I've not used bourne shell in over 20 years, and the following might work should this be a newer more posix standard bourne.

test the variable for how many characters it contains.

Code:

if [ ${#W} -eq 0 ]
then
  echo "please enter value for W: \c"
  read W_input
fi

OR, set the variable to a unused value early in the script, and then check if changed.

Code:

W="empty"

if [ "${W}" == "empty" ]
then
  echo "please enter value for W: \c"
  read W_input
fi

HTH

Thanks for the reply. My question was actually related to looping this. For example

for i in W X Y Z
do
if [ ! -n "${i}" ]
then echo "Please enter a value for i: \c"
read i
fi

The problem with this script is that ${i} is equal to W or X ...., and not the actual value of the variable. I am having hard time getting the right logic to code it.

Thanks.

hi nimo
what do you want exactly?

These are the steps that I am trying to do:
1. Start script and read few env variables that should be set; ie: W, X, Y & Z
2. Run a loop to check that the variables are not empty