Question

I read the manual at http://www.gnu.org/software/emacs/manual/html_node/elisp/Saving-Buffers.html#Saving-Buffers, but still not quite understand what is the difference between the two. It seems to me they both work as a hook to run whatever function you set before saving the buffer to the visited file. could anyone explain with examples? Thanks.

Answer 1

write-*-functions provide a strict superset of what before-save-hook can do. More specifically, write-*-functions can replace the normal saving mechanism with another one. This means that a function added to write-*-functions might end up unused because some earlier function has already saved the buffer.