Use parameter expansion instead of basename

wait-for-it.sh

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 #   Use this script to test if a given TCP host/port are available
 
-cmdname=$(basename $0)
+cmdname=${0##*/}
 
 echoerr() { if [[ $QUIET -ne 1 ]]; then echo "$@" 1>&2; fi }