UNIX for Dummies Questions & Answers

# Two empty folders.
$ mkdir local remote
# Each has another "a" folder in it.
$ mkdir local/a remote/a
# The "a" we want to keep has a "this" file containing "olddir".
$ echo olddir > local/a/this
# the one we don't want has a file containing "newdir"
$ echo newdir > remote/a/this
# a folder to bind things to temporarily
$ mkdir bind
# bind the "a" we want to keep onto 'bind'
$ mount --bind local/a bind
# Bind the new dir on top of the old, like you were doing
$ mount --bind remote local
$ cat local/a/this
newdir
# bind the old "a" folder overtop of the new one
$ mount --bind bind local/a
# We now have the 'remote' folder bound overtop of the 'local' one,
# but with the old 'a' folder bound overtop of it!
$ cat local/a/this 
olddir
$