Renaming files in a UNIX directory - shell scripting

Question

I have been trying to write a script that will take the current working directory, scan every file and check if it is a .txt file. Then take every file (that's a text file), and check to see if it contains an underscore anywhere in its name and if it does to change the underscore to a hyphen.

I know that this is a tall order, but here is the rough code I have so far:

#!/bin/bash
count=1
while((count <= $#))
       do
          case $count in
               "*.txt") sed 's/_/-' $count
          esac
          ((count++))
done

What I was thinking is that this would take the files in the current working directory as the arguments and check every file(represented by $count or the file at "count"). Then for every file, it would check if it ended in .txt and if it did it would change every underscore to a hyphen using sed. I think one of the main problems I am having is that the script is not reading the files from the current working directory. I tried included the directory after the command to run the script, but I think it took each line instead of each file (since there are 4 or so files on every line).

Anyway, any help would be greatly appreciated! Also, I'm sorry that my code is so bad, I am very new to UNIX.

Answer 1

for fname in ./*_*.txt; do
  new_fname=$(printf '%s' "$fname" | sed 's,_,-,')
  mv "$fname" "$new_fname"
done

Answer 2

为什么不：

rename 's/_/-/' *.txt

Answer 3

$ ls *.txt | while read -r file; do echo $file | 
  grep > /dev/null _ && mv $file $(echo $file | tr _ -); done

(untested)

Answer 4

Thanks for all your input guys! All in all, I think the solution I found was the most appropriate for my skill level was:

ls *.txt | while read -r file; do echo file |
   mv $file $(echo $file | sed 's,_,-,');
done

This got what I needed done, and for my purposes I am not too worried about the spaces. But thanks for all your wonderful suggestions, you are all very intelligent!