Join several cbr or cbz files within in one single big cbz file, the order of the files in the final file will be determined alphabetically.

joincbzr.sh

#!/bin/bash

if [ -z "$1" ]
then
    echo "Specify the name of the file to create and the directory with the cbr files."
    echo "./joincbr.sh YOUR_COMIC_FILE SOURCE_DIRECTORY"
    exit 0
fi

TARGET_NAME=$1
SOURCE_DIRECTORY=$2

export count=0
find -E "$SOURCE_DIRECTORY" -regex '.*\.(cbr|cbz)' -type f  -print0 | sort -z |while IFS= read -r -d '' file; do
	extension=${file/*./}
	dest=$(printf %06d $count)/
	if [ "$extension" == "cbr" ]; then
		unrar x "$file" "$dest"
	else
		unzip -a "$file" -d "$dest"
	fi
	((count++))
	zip -ur "$TARGET_NAME.cbz" "$dest"
	rm -fr "$dest"
done