How can I organize files based on their filename first letter into A-Z folders

A late python option:

#!/usr/bin/env python3
import os
import sys
import shutil

def path(dr, f): return os.path.join(dr, f)

dr = sys.argv[1]
for f in os.listdir(dr):
    fsrc = path(dr, f)
    if os.path.isfile(fsrc):
        s = f[0]; target = path(dr, s.upper()) if s.isalpha() else path(dr, "#")
        if not os.path.exists(target):
            os.mkdir(target)
        shutil.move(fsrc, path(target, f))

How to use

1. Copy the script into an empty file, save it as move_files.py

2. Run it with the directory as argument:

   python3 /path/to/move_files.py /path/to/files
   

The script will only create the (sub) directory(-ies) (uppercase) if it is actually needed

Explanation

The script:

• lists the files, gets the first character (defines the sourcepath):

  for f in os.listdir(dr):
      s = f[0]; fsrc = path(dr, f)
  

• checks if the item is a file:

  if os.path.isfile(fsrc):
  

• defines the targeted folder for either if the first char is alpha or not:

  target = path(dr, s.upper()) if s.isalpha() else path(dr, "#")
  

• checks if the folder already exists or not, creates it if not:

  if not os.path.exists(target):
      os.mkdir(target)
  

• moves the item into its corresponding folder:

  shutil.move(fsrc, path(target, f))
  

Code-golfed yet readable with just two commands and two regular expressions:

mkdir -p '#' {a..z}
prename -n 's|^[[:alpha:]]|\l$&/$&|; s|^[0-9]|#/$&|' [[:alnum:]]?*

If you have a huge amount of files to move, too many to fit into the process argument list (yes, there's a limit and it may be just a few kilobytes), you can generate the file list with a different command and pipe that to prename, e. g.:

find -mindepth 1 -maxdepth 1 -name '[[:alnum:]]?*' -printf '%f\n' |
prename -n 's|^[[:alpha:]]|\l$&/$&|; s|^[0-9]|#/$&|'

This has the added benefit of not trying to move the literal file name [[:alnum:]]?* if no files match the glob pattern. find also allows many more match criteria than shell globbing. An alternative is to set the nullglob shell option and close the standard input stream of prename.¹

In both cases remove the -n switch to actually move the files and not just show how they would be moved.

Addendum: You can remove the empty directories again with:

rmdir --ignore-fail-on-non-empty '#' {a..z}

---

¹ shopt -s nullglob; prename ... <&-

I didn't work out a nice way to make the directory names uppercase (or move the files with uppercase letters), although you could do it afterwards with rename...

mkdir {a..z} \#; for i in {a..z}; do for f in "$i"*; do if [[ -f "$f" ]]; then echo mv -v -- "$f" "$i"; fi; done; done; for g in [![:alpha:]]*; do if [[ -f "$g" ]]; then echo mv -v -- "$g" \#; fi; done

or more readably:

mkdir {a..z} \#; 
for i in {a..z}; do 
  for f in "$i"*; do
    if [[ -f "$f" ]]; then 
      echo mv -v -- "$f" "$i"; 
    fi 
  done
done
for g in [![:alpha:]]*; do 
  if [[ -f "$g" ]]; then 
    echo mv -v -- "$g" \#
  fi
done

Remove echo after testing to actually move the files

And then

rename -n 'y/[a-z]/[A-Z]/' *

remove -n if it looks good after testing and run again.