How can I edit my bash script to account for whitespace entries?

Question

I made a script to automate ffmpeg conversion from mkv > m4v > open the m4v in Subler.app to import the metadata manually, at which point I'll move the file into my iTunes library.

I use iTunes because I have two Apple TVs on the network and use a 2007 iMac to function as my media server. I locally ssh into this machine in order to execute this script.

This script fails if I enter a path with whitespace(s), or enter title for the movie that includes whitespace. How do I fix this script to accommodate whitespace? I know the syntax is sloppy, I’m very new to scripting, so any other pointers to make it run better would be appreciated :)

Here it is:

    #! /bin/bash

#ffmp4

function convert {
    ffmpeg -i $REPLY -strict -2 -c:v copy -c:a copy -c:s copy $PWD/out.m4v
}

function rename {
    echo "Please Provide the Title:"
    read -e; mv $PWD/out.mp4 $PWD/$REPLY.m4v
}

function subler {
    open -a Subler.app $REPLY.m4v
    } 

cd ~/Public/ &&
while read -e; do
    if [ ${REPLY: -4} == ".mkv" ]; 
    then convert;
        rename;
        subler;
        exit 
    else 
    echo "Error: This is not a valid response" && exit 1
    fi
done

—————————

EDIT:

Question may still be a possible duplicate, but I’ve tried to use the syntax (both attempting “$REPLY” and “$(REPLY)”) in the linked answer and still failing to execute. The errors return either bad substitution for the […bracketed...] statement or my echo statement... Error:This is not a valid response…

Answer 1

So, guidance + trial and error led me to solution. I quoted the “$REPLY” variable as suggested…but I also needed to [[…]] instead of […] for the script to execute properly. I’m not exactly sure why, but now it’s working nonetheless. Thank you SE community!