Dired Example One

Say we would like to rename all files named *.shtml.wml into *.php.wml in a certain directory such as /tmp. You may know of the Linux CLI tool mmv with which we could do:

$ mmv '*.shtml.wml' '#1.php.wml'

but what if we are on a system where mmv is not available? Shall we try to install it or write a little script to achieve what we want?

What about using Emacs's dired and its dired-do-rename-regexp command (bound on % R) instead. Firstly, press C-x d /tmp RET to launch dired on our working directory (or dired /tmp in the eshell). Then use this dired file regexp renaming command:

% R ^\(.*\)\.shtml\.wml$ RET \1.php.wml RET

and press y or n or ! to rename some or all of the matched files, and we are done.

Dired Example Two

We are moving away from javadoc-style of docstrings to epydoc-style of docstrings in our coding project, so we would like to replace all occurrences of @param foo bar by @param foo: bar recursively in all our sources.

Firstly, search for all the files containing @param something space, i.e. when the variable name not followed by a colon, and let us make a dired buffer out of these files, by means of find-grep-dired:

M-x find-grep-dired RET ~/src/cds-invenio/modules RET @param \(\w*\) SPC RET

Secondly, in the dired buffer, mark only the Python files for further processing:

% m \.py$ RET

Thirdly, replace wanted expressions in the preselected files:

Q @param \(\w+\) SPC RET @param \1: SPC RET

Now choose interactively y or n to replace or not the given occurrence of the param regexp, or use ! to replace silently every occurrence, etc.

Finally, save all buffers:

C-x s !

and we are done.

Another advantage of doing these replacements inside Emacs itself rather than via CLI one-liners is a much better interactivity: we can easily test our regexps, replace only some occurrences while not touching others, revert some of the edits back, etc.