Help with a basic shell script

[Richard Pruitt]

I have written a script that allows my admins to add a user to our SFTP server.  I have one problem:   How do I verify if a user already exists?    I have this, but it gives me unary error when the user doesn't exist because it doens't output a numeric value.   #!/bin/sh   echo -n "What is the username?" read var1   var2=`/usr/bin/id -u $var1`      if [ $var2 -gt 499 ] ; then      echo "This user already exists."    else       echo "This user does not exist."    fi