krbroot: Handle unset ATHENA_USER

diff --git a/krbroot b/krbroot
index 37e04294f6b2ec103a56ded9352323d54e03a6f5..e1d7f9d59382822e89504df1e0205cf97ec26744 100755 (executable)
--- a/krbroot
+++ b/krbroot
@@ -4,6 +4,7 @@ set -euf
 
 usage="Usage: $0 [-i instance] [-p principal] [-a addrend] subcommand [args]"
 
+ATHENA_USER=${ATHENA_USER:-$USER}
 principal="$ATHENA_USER/root@ATHENA.MIT.EDU"
 addrend="root"
 while getopts "i:p:a:h" options; do