I've learned that nobody and nothing should use /tmp, on account of it being 777. The idea is that Mallory can set up a symlink from an anticipated filename ("

I've learned that nobody and nothing should use /tmp, on account of it being 777. The idea is that Mallory can set up a symlink from an anticipated filename ("things" in your example) to an important file or dir. So writing to /tmp/things destroys the symlinked file/dir.