Batch File Renaming With Zsh¶

I recently discovered zmv, a builtin feature of zsh that makes batch file renaming, a breeze.

To use it you need to add this to your zsh configuration file (.zshrc).

autoload zmv

My blog contains several Markdown files with a .markdown extension and I want to use .md instead.

ls **/*.markdown

./drafts/2012-05-06-learning-ruby-and-ruby-on-rails.markdown
./drafts/2015-07-19-welcome-to-jekyll.markdown
./posts/2012-02-10-baked-with-octopress.markdown
./posts/2015-08-15-batch-rename-files-with-zsh.markdown
./posts/2015-08-15-octopress-3-0.markdown
./about/index.markdown
./contact/index.markdown

Note I used the double star zsh notation to recursively list the files with the .markdown suffix.

**/ will match the current directory or (recursively) any directory below it.
*.markdown will match any file with the .markdown suffix.

ls **/*.markdown is shorter than the alternative find . -name '*.markdown'.

Now, zmv comes in handy to recursively change the extension from .markdown to .md.

zmv '(**/)(*).markdown' '$1$2.md'

where:

() are used n the source part to capture what is inside the parenteses, for example when processing contact/index.markdown
(**/) captures the path without the filename: contact/ (in our example)
(*) captures the filename without the suffix: index
$1 will be replaced by whatever was captured by the first pair of parentheses: contact/
$2 will be replaced by whatever was captured by second pair of parenteses: index

This means that when processing contact/index.markdown,
zmv will do something similar to mv contact/index.markdown contact/index.md.

Voilà, the files have been renamed!

ls **/*.md

./drafts/2012-05-06-learning-ruby-and-ruby-on-rails.md
./drafts/2015-07-19-welcome-to-jekyll.md
./posts/2012-02-10-baked-with-octopress.md
./posts/2015-08-15-batch-rename-files-with-zsh.md
./posts/2015-08-15-octopress-3-0.md
./about/index.md
./contact/index.md

Check your zmv command without actually running it

You can use the -n option to ask zmv to print what it would do without actually doing it.
This gives you an opportunity to check that everything is ok before running the command to prevent you from doing a lot of back and forth only because of a typo in the command.

zmv -n '(**/)(*).markdown' '$1$2.md'

mv drafts/2012-05-06-learning-ruby-and-ruby-on-rails.markdown drafts/2012-05-06-learning-ruby-and-ruby-on-rails.md
mv drafts/2015-07-19-welcome-to-jekyll.markdown               drafts/2015-07-19-welcome-to-jekyll.md
mv posts/2012-02-10-baked-with-octopress.markdown             posts/2012-02-10-baked-with-octopress.md
mv posts/2015-08-15-batch-rename-files-with-zsh.markdown      posts/2015-08-15-batch-rename-files-with-zsh.md
mv posts/2015-08-15-octopress-3-0.markdown                    posts/2015-08-15-octopress-3-0.md
mv about/index.markdown                                       about/index.md
mv contact/index.markdown                                     contact/index.md