As far as I can tell (tested on Linux & Darwin, BSD man page seems to agree), `-d` is pretty univerally accepted as the depth argument. So instead of doing a test, we can just use -d and call it a day.
@@ -38,7 +38,7 @@ alias -g NE="2> /dev/null"
alias -g NUL="> /dev/null 2>&1"
alias -g P="2>&1| pygmentize -l pytb"
-alias dud='du --max-depth=1 -h'
+alias dud='du -d 1 -h'
alias duf='du -sh *'
alias fd='find . -type d -name'
alias ff='find . -type f -name'