Dired mode (M-x dired <RET>, or C-x d) supports the
dired-do-find-regexp-and-replace (Q), which allows
users to replace regular expressions in multiple files.
You can use this command to perform search/replace operations on multiple files by following the following steps:
query-replace-regexpsession on the marked files.
Another way to do the same thing is to use the “tags” feature of
Emacs: it includes the command
tags-query-replace which performs
a query-replace across all the files mentioned in the TAGS file.
See Identifier Search.