Some GNU programs (at least cp and mv) allow you to
remove any trailing slashes from each source argument before
operating on it. The --strip-trailing-slashes option enables
this behavior.
This is useful when a source argument may have a trailing slash and
specify a symbolic link to a directory. This scenario is in fact rather
common because some shells can automatically append a trailing slash when
performing file name completion on such symbolic links. Without this
option, mv, for example, (via the system’s rename function) must
interpret a trailing slash as a request to dereference the symbolic link
and so must rename the indirectly referenced directory and not
the symbolic link. Although it may seem surprising that such behavior
be the default, it is required by POSIX and is consistent with
other parts of that standard.