I had to replace all filenames in a folder, recursively, with space with underscore.

This is one of the one-off operations I need to do while working on my website, and I don’t really want to, for example, search, install (buy) an app just to do that.

Here’s the Fish Shell script I used:

#!/opt/homebrew/bin/fish

# define the directory to search
set search_dir ./

# recursively find all files in the search directory
find $search_dir -type f | while read -l file
    # replace spaces with underscores in the file name
    set new_name (echo $file | tr ' ' '_')

    # rename the file
    mv $file $new_name
end

I put this in the folder containing all the files and folders I wanted to rename, named replace_spaces.fish.

Then I set it as executable using chmod +x replace_spaces.fish and finally ran it using ./replace_spaces.fish.

Lessons in this unit:

0:	Introduction
1:	Introduction to Shells
2:	Bash Basics
3:	Writing Shell Scripts
4:	Variables and Environment Variables
5:	Loops and Arrays
6:	Shell Script Functions
7:	Creating Aliases
8:	Tips and Tricks
9:	The Fish Shell
10:	Persist aliases and other configuration in Fish Shell
11:	How to add a path to Fish Shell
12:	Fish Shell, how to avoid recording commands to history
13:	Fish Shell, how to remove the welcome message
14:	▶︎ How to replace all filenames with space with underscore using a shell script
15:	How to update all npm packages in multiple projects that sit in subfolders