emacs - Replace regexp / string / words in several / multiple files

In short:

M-x dired-do-query-replace-regexp

Longer version:

To replace the same regexp, string or word in multiple files go into dired mode

C-x C-f RET

Then you should see a list of files.

Mark the files you want to edit with m.

To mark all files press t (M-x dired-toogle-marks).

You can also mark only all files but some: First mark the files which you don't want to be marked (by using m) and then press t.

All the other files get marked.

To mark files using a regular expression, e.g. to mark all .tex files you can use following key combination in dired mode

*%

To replace a certain string or regular expression (regexp) in all marked files

M-x dired-do-query-replace-regexp

Options during replacing:

• C-g  (stopps the replacing)
• ! (replace the regexp string in the current file without asking)
• N (do no further replacements in this file)
• Y (replace all occurrences in all files, without asking)

Saving the modified buffers

1st way

C-u C-x s

This saves all modified files silently, i.e. without asking for confirmation.

2nd way

M-x ibuffer
*u (marks all modified buffers)
S (capital 'S', saves all marked buffers)
D (kills the marked buffers)