Vim: Substitute in all buffers

To replace all instances of FOO with BAR in one file, you’d do:

:%s/FOO/BAR/g|:up

The pipe | lets you separate multiple commands and :up is like :w but only writes changed buffers.

Now for all open files:

:bufdo :%s/FOO/BAR/g|:up

Roughly translates to: for all open buffers, substitute FOO with BAR and write the changes.