check for zero length strings

diff --git a/system/selftest b/system/selftest
index 02753ea..47b72f8 100755 (executable)
--- a/system/selftest
+++ b/system/selftest
@@ -3,8 +3,8 @@
 SELF_HOST=$1
 SELF_IP=$2
 # all below addresses are those of the qemu host
-[ -n "$SELF_HOST" ] && SELF_HOST="selftest.$(hostname)"
-[ -n "$SELF_IP"   ] && SELF_IP="10.1.159.48"
+[ -z "$SELF_HOST" ] && SELF_HOST="selftest.$(hostname)"
+[ -z "$SELF_IP"   ] && SELF_IP="10.1.159.48"
 
 
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