use a case statement rather than a bash substring, for portability

z.sh

@@ -98,8 +98,10 @@ _z() {
   [ "$fnd" ] || local list=1
 
   # if we hit enter on a completion just go there
-  # completions will always start with /
-  [ -z "$list" -a -d "$last" -a "${last:0:1}" = "/" ] && cd "$last" && return
+  case "$last" in
+   # completions will always start with /
+   /*) [ -z "$list" -a -d "$last" ] && cd "$last" && return;;
+  esac
 
   # no file yet
   [ -f "$datafile" ] || return