#!/bin/bash
for FILE in *.txt
do
   DIR=${FILE##*_}
   DIR=${DIR/.txt/}
   [ ! -d $DIR ] && mkdir $DIR
   mv $FILE $DIR
done
[download]

PerlMonks graciously bestowed by Tim Vroom.
PerlMonks went on a couple dates, and then decided to shack up with The Perl Foundation.
Beefy Boxes and Bandwidth Generously Provided by pair Networks
Built with the Perl programming language.