I am assuming you have files like,

[a-s]_dragon_ball_-_001_-_the_secret_of_the_dragon_balls__rs2_[4FC1375C]

[a-s]_dragon_ball_-_002_-_the_emperors_quest__rs2_[59F9C743]

[a-s]_dragon_ball_-_003_-_the_nimbus_cloud_of_roshi__rs2_[0C592F5F]

[a-s]_dragon_ball_-_004_-_oolong_the_terrible__rs2_[47CE4923]

[a-s]_dragon_ball_-_005_-_yamcha_the_desert_bandit__rs2_[B6A035BF]

these files have [a-s] at beginning. And you want them after rename as, (according to your comment)

001_-_the_secret_of_the_dragon_balls

002_-_the_emperors_quest

003_-_the_nimbus_cloud_of_roshi

004_-_oolong_the_terrible

005_-_yamcha_the_desert_bandit

Use this script below,

#!/bin/bash

for file in [[a-s]]*

do

    newfile=`echo "$file" | sed -r "s/^.{20}//" | awk -F "__rs2" '{print $1}'`

    mv $file $newfile

done

How it work

This script scans all filenames in current directory that starts with "[a-s]". Next inside for loop for every scanned file name the script creates new file name leaving first 20 characters filtered throughsed and cuts part starting with string "__rs2" . That removes unwanted parts in the name. And lastly the files are renamed to new file name one by one.

Usage

Save the code as rename_file.sh.(say) Next put it at the same directory where all these files are. Give the script execution permission. Write in terminal,

chmod +x rename_file.sh

Finally to rename the files, just write in terminal,

./rename_file.sh

Done.