A zsh script to extract the largest DMG from an IPSW to the same folder with the label as name

ipsw2dmg.sh

#!/bin/zsh
# ipsw2dmg.sh by github.com/atnbueno - v2.0.0 (2022-07-31) - License: MIT

# Check if input file exists (with or without an .ipsw extension)
if [ -f "$1" ]; then
    INPUT=$(realpath "$1")
else 
    if [ -f "$1.ipsw" ]; then
        INPUT=$(realpath "$1.ipsw")
    else 
        ERR="Input file ($1) not found"
    fi
fi

# Check that the script is called with two parameters
if [ $# -lt 2 ]; then
    ERR="The script requires two parameters"
fi

if [ -n "${ERR}" ]; then
    autoload -U colors && colors # necessary to colorize the feedback to the user
    echo $fg[green]ipsw2dmg extracts the largest DMG from an IPSW to the same folder with the label as name
    echo $fg[red]ERROR: $ERR
    echo $fg[yellow]Usage: ipsw2dmg.sh input.ipsw label.dmg$reset_color
else
    IPSW=$(basename "$INPUT" .ipsw)
    LABEL=$(basename "$2" .dmg)
    DMG=$(unzip -l "$1"|sort|grep dmg|tail -1|cut -c32-)
    CD=$PWD # remember the current directory
    cd ${INPUT%/*} # work where the input file is
    unzip -o "$IPSW.ipsw" "$DMG"
    mv -f "$DMG" "$LABEL.dmg"
    read -q "ANSWER?Delete input file (y/N)? " # interactive question
    echo # finish the line to avoid a highlighted "%"
    if [[ "$ANSWER" == "y" ]]; then # -q returns "y" if input is "y" or "Y", "n" otherwise
        rm "$1"
    fi
    echo "$LABEL.dmg" can be found at $PWD:
    ls -la *.dmg # show the new file along any other DMG in the same folder
    cd $CD # go back to the original directory
fi