@david: sounds like you've never been bitten by intending a simple rename or move presumably within a filesystem and seeing mv instead launch into copying. if i want a copy i'll use cp. and i'll have a look before i rm any original. those safety checks you refer to are almost entirely around the copy, which i don't even want. rhel rename comes with util-linux-ng, ubuntu rename comes packaged with perl, neither manpage has the WARNING you mention. reads like the author had something ominous in mind but they don't say what. would rename consent to lose a directory within it's children? you mean to suggest mv protects you in some important way from something rename might do? my understanding of mv is if rename(2) succeeds, it's done, but if not, well that's when the trouble begins.. @munir: and there is no reliable test for "same filesystem". even /proc/mounts is not always reliable, eg with persistence ala overlayfs, or if /proc itself is unavailable, eg in a chroot