It will also refuse to rename a file over an existing filename unless you force it to with -f. There's little or no need to exclude files that don't contain a space because perl rename will only attempt to rename a file if the filename was actually changed by your rename script, and the script above won't change filenames without a space. Once you're sure it does what you want, remove the -n option or replace it with -v for verbose output. The -n option makes this a dry-run, it won't actually rename any files, it will just show you what would be renamed. Then you can replace spaces with underscores in all filenames + directory names in the current directory with just: rename -n 's/ /_/g' * Again, if you don't have Homebrew installed on your Mac, you should, it gives you access to thousands of packages. If you have Homebrew installed, you can install it with brew install rename (see rename on brew), otherwise you can install it with cpan. If you don't already have it, you should install it - it makes difficult bulk-renaming operations trivially easy.

I weight the issues of cost/complexity/frequency of use before I take on new software.If you have the perl rename utility, File::Rename, already installed, this is easy. I’ve generally avoided add-ons as I try to keep things as vanilla as possible to forestall problems. UPDATE: see Quick Look: A Better Finder Rename. MPG: I have not looked into these products, but a quick look suggests they are vastly superior to the macOS Finder. They’re not free like the Finder feature, but are vastly more capable. The ‘Big Mean Folder Machine’ is also a good app when managing large hierarchical libraries: It’s great for OCD file organization.(After using it in trial mode I was impressed enough to buy the ‘Forever Upgrade’ a number of years ago, and have benefitted ever since.)

I have used it for normalizing many filenames (thousands at a time) from disparate sources, along with folder names. It’s a fantastically-capable batch processor.

I think including the word ‘Finder’ in the app name makes it sound like it’s some sort of extension. If you don’t already use it, I highly recommend ‘A Better Finder Rename’: Renaming files to include date and time Don H writes:

Macos rename