Automate folder creation with specified name using Bash Script

I've been creating new folder with a specific naming pattern in the Terminal.
A folder named /dayX-title that contains a README.md file.

E.g: /codingclub/challenge/dayX-title/README.md

linxea at tmo in ~/codingclub/challenge
$ ls
day0-the-beginning-of-the-coding-club
day1-may-the-odds-be-in-your-favour
day2-so-far-so-good
day3-oh-man

This is how I create a new file in a new folder. I manually look through the list of folders to get the next count. Then type the title-with-dash-and-dash-and-dash.

$ touch day4-time-to-automate/README.md

I'm getting lazy so we'll write a bash script to do that.

I'm looking to write a commmand ./new time to automate to create /day4-time-to-automate with a README.md in it.

Steps:

1. Iterate through all the folders
2. Find the largest number of day
3. Create a new folder with a README.md file with the given input filename

#!/bin/bash

# Take in all arguments in one variable
input="$*"
folderTitle=$input

# Check if there is input, otherwise exit script
if [[ -z "${folderTitle// }" ]]; then
  echo "Where is your awesome title yo?"
  exit 1
fi

# Replace space to -
folderTitle=${folderTitle// /-}

# Loop through the list of directories and find the biggest number
biggestNumber=-1
for dir in $(ls)
do
  number=`sed 's/[^0-9]//g' <<< $dir`
  if (( number > biggestNumber )); then
    biggestNumber=$number
  fi
done

# Increment the biggest number by 1
((biggestNumber=biggestNumber+1))

# Create a new folder and README.md file
newName=day$biggestNumber-$folderTitle
mkdir -p $newName
echo -e "TITLE: Day $biggestNumber $input\n" > $newName/README.md

# Print success message to make me feel good
echo Created $newName yo 🦄

Tada, now you just have to make the script executable by running chmod -x and run the command ./new.sh with title after that.

$ chmod -x new.sh # make the script executable
$ ./new.sh as usual this task takes longer than i expected

Uploaded my script to Repl.it, check it out at https://repl.it/@linxea/Create-New-Folder-and-File . You may need to login to play with it.

DOES IT WORTH THE TIME TO PICK UP BASH TO AUTOMATE SUCH A TINY MATTER?

a tiny yes.

Another Problem Another Day to Solve,

I wanted to extract the number 123 between day123-title-that-may-contain-123 using sed but regex is messing with my mind. 🤯 How do I do that? How to I write a regex that only returns number between day and -everything-else-after-dash? Explain regex like I'm 5 please.

End