organizing long list of txt files

brach_fix.sh

#!/bin/bash
DIR=/home/parse/big_lists2/
i=1
for fullfile in $DIR*.txt; do
    filename=$(basename -- "$fullfile")
    extension="${filename##*.}"
    filename="${filename%.*}"
    hash=$(md5sum "${fullfile}"|cut -d' ' -f1)
    echo "Moving" $filename".txt to "$filename
    echo "[$i] Making directory folder_$i"
    mkdir $DIR"folder_"$i
    echo "[$i] Move "$filename".txt to folder_"$i" renamed to "$hash".txt"
    mv $filename".txt" $DIR"folder_"$i/$hash.txt
    echo "[$i] Enter dir "$i
    cd $DIR"folder_"$i
    echo "[$i] Split files"
    split -l 100000 --additional-suffix=.txt --numeric-suffixes $hash".txt" $i"_"
    echo "[$i] Delete hash file"
    rm $hash.txt
    echo "[$i] Move new files to root directory"
    mv *.txt ..
    echo "[$i] Deleting folder $i"
    cd .. && rm -rf folder_$i
    echo "----------------------------------------------------"
    
    i=$((i+1))
done

#------------------

# Rename all files for its hash

for file in *.txt; do hash=$(md5sum "${file}"|cut -d' ' -f1) && echo $file $hash.txt && mv $file $hash.txt; done

#-----------------

# Rename all hash to number