Script shell arborescence

#!/bin/bash
if -n "$1"; then
 echo "Usage : " $0 " command";
 echo "Exécute command dans tous les sous-répertoires du dossier courant.";
else
  for i in ./*
  do
    if [ -d "$i" ]
    then
      $1 $i;
    fi
  done
fi

#!/bin/bash

test -z "$1" && { echo usage: $0 commande ; exit 1 ; }
HERE=$PWD
du | ( while read T D ; do
        cd "$D"
        $1
        cd $HERE
done) 

$ cat ~/f1
#!/bin/sh
test -z "$1" && { echo usage: $0 commande ; exit 1 ; }
CMD="$@"
fx()
{
	for F in $(ls -a|egrep -v '^\.$|^\.\.$')
	do test -d $F -a ! -h $F -a -r $F && { cd $F ; fx $F ; cd .. ; } ; done
	$CMD
}
fx $PWD

$ cd /tmp
$ mkdir -p a/b/c/d
$ cd a
$ ~/f1 pwd
/tmp/a/b/c/d
/tmp/a/b/c
/tmp/a/b
/tmp/a
$