Truncating the length of files\directors to 31 characters or less

daysleeper · 09-26-2006, 09:33 AM

Hi guys,

I've literally got thousands of files\directories that are between 50-60 characters in length and I need to rename them or simply just cut of anything in the filename after the 31st character so the new filenames are no longer than 31 characters. The files are mp3's

Does anyone know if I could create a script in bash or tcsh that would allow me to automate this function?

Basically after specifying a directory (eg. /name) it would need to recursively scan all the subdirectories and files, check their length and if they are longer than 31 characters simply cut off everything after the 31st character. eg. A file like "ThisFileIsJustWayTooLongAndReallyNeedsToBeShortened.mp3" would become "ThisFileIsJustWayTooLongAnd.mp3" Catch is it needs to keep the .mp3 extension. Although all the files are mp3's so I could always trucate to 27 characters and then add .mp3 to the filename.

I'm very new to linux scripting but have some programming knowledge. I would be very gratefull for a push in the right direction of if there is already a program that could do this.

Thanks,
Daysleeper

J.W. · 09-26-2006, 01:21 PM

I guess my main question would be, What is your real goal here? Simply lopping off anything past the "Nth" character could easily result in having multiple files having the same name. To re-use your example, suppose you had

Code:

"ThisFileIsJustWayTooLongAndReallyNeedsToBeShortened_Track_1.mp3" 
"ThisFileIsJustWayTooLongAndReallyNeedsToBeShortened_Track_2.mp3" 
"ThisFileIsJustWayTooLongAndReallyNeedsToBeShortened_Track_3.mp3" 
....

Using the truncation approach, they'd all become "ThisFileIsJustWayTooLongAnd.mp3" and that wouldn't work.

Can you provide the background as to why this operation is necessary, or what the update is intended to accomplish?

kloss · 09-26-2006, 04:43 PM

Code:

#!/bin/sh
  find . -regextype posix-extended -regex ".*/[^/]{32,}" | while read file; do
  name=`basename "$file"`
  echo "$file" "${file%$name}${name::27}.mp3"                                            
done

This script is basically what you want. Just s/echo/mv and add a line to take JW's comment in account, since he's right. If it screws up your box and eat your cat, I'm not responsible.

daysleeper · 09-27-2006, 12:28 AM

Thanks for the reply guys. I realise that I could end up with multiple files with the same name but after looking at the files I'm pretty sure that the first 30 characters are defintely unique. The reason I'm doing this is that I work for a sound studio and we have been supplied with a digital music library. The new Macs (OSX) can handle very long file names but the old Macs (OS9x) have the file length limitation. Many thanks for the script, will give it a try /