Fix string comparison

zshrc

@@ -28,7 +28,7 @@ printable-code()
 }
 
 # make the clipboard working on remote
-if [[ "$SSH_CLIENT" ]]; then
+if [[ -n "$SSH_CLIENT" ]]; then
   SSH_IP=$(echo $SSH_CLIENT | awk '{print $1}')
   alias pbcopy="ssh $SSH_IP pbcopy"
 fi