while loop question

Shell Programming and Scripting
1

while [ $dev_num ]
do
print What is the next device number to be added to $dgroup?
print Press \<Enter\> if there are no more devices to be added.
read dev_num
export dev_num
symld -g $dgroup -sid $sname add dev $dev_num
done

In this while loop, how do I stop it from running the final command if <Enter> is pressed? Currently, if a user presses <enter> it will still run
symld -g $dgroup -sid $sname add dev
I'm not sure how to skip this command if a user just presses <Enter>

Thanks

Edit: Forgot to mention this is the ksh

2

Here is one way of doing:

while true
do
  print What is the next device number to be added to $dgroup? 
  print Press \<Enter\> if there are no more devices to be added.
  read dev_num
  if [ "${dev_num}" = "" ]; then
    exit
  fi
  export dev_num
  symld -g $dgroup -sid $sname add dev $dev_num
done
3

exit != break