Read response and if then else loop - bash

Question

I have this piece of rudementary code in my .bash_profile that loads on login, but I can't get it working. Probably some easy fix, but I', staring my self blind on it right now.
The code:
# Simple backup when editing files with nano
function bu() {
read -p "Backup >>"`basename $1`"<< b4 edit [Y/n]?" response
echo $response
response=$response${response,,} # tolower
if [[ $response =~ ^(yes|y| ) ]]; then
mkdir -p ~/.backup
#cp -v "$1" ~/.backup/`basename $1`-`date +%Y%m%d%H%M`.backup
cp "$1" ~/.backup/`basename $1`-`date +%Y%m%d%H%M`.backup
echo ~/.backup/`basename $1`-`date +%Y%m%d%H%M`.backup >> ~/.backup/bu_log.txt
nano "$1"
else
nano "$1"
fi
}
And it has an alias nano="bu"
so, when i write nano, it should ask me if i want to backup the file first (on yes) or just open it in nano straight away.
The only thing that happens now is that it keeps asking the question and looping, newer goes to nano.
CentOS is the linux

Answer 1

Since nano is an alias to bu, typing nano runs your function, which calls nano, which is an alias to bu, which calls nano, ...
In order to run the actual nano editor, you need to disable alias expansion for that call. Use the command built-in:
command nano "$1"

Answer 2

You are calling nano recursivly, since you aliased nano=bu
so try to change the line in the script
nano "$1"
to the full path of
/usr/bin/nano "$1"
(or where nano is installed on your system)

Answer 3

I think you want:
response=${response,,}
You have
response=$response${response,,}
which gets you response=Yy. That won't match your regular expression.
You could also just do shopt -s nocasematch.
Aliases are usually trouble. The rule is "if in doubt, use a function."
nano() {
bu "$#"
}
bu() ( # Use a subshell to avoid having to reset shell options
shopt -s nocasematch
local base=${1##*/}
read -p "Backup >>${base}<< b4 edit [Y/n]?" response
case $response in
y*)
mkdir -p ~/.backup
local backup=~/.backup/"${base}-$(date +%Y%m%d%H%M`).backup"
cp "$1" "$backup"
echo "$backup" >> ~/.backup/bu_log.txt
;;
esac
command nano "$#" # Use "$#" to allow you to pass more than one argument to nano
)