ファイル名をすべて大文字/小文字にする

#!/bin/sh
#large_f.sh

. f_askdir.sh

ask_directory 1
if [ $? -eq 1 ]; then
    exit 1
fi

CURRENTDIR=$(pwd)
cd $_DIRNAME

if [ $(ls | wc -l) -eq 0 ]; then
    echo "No file."
else
    for FNAME in * ; do
        FNAMEL=$(echo $FNAME | tr '[a-z]' '[A-Z]')
#       FNAMEL=$(echo $FNAME | tr '[A-Z]' '[a-z]')
        mv $FNAME $FNAMEL
    done
fi

cd $CURRENTDIR
unset _DIRNAME CURRENTDIR FNAME FNAMEL

$ ls
a001.txt  a003.txt  a005.txt  a007.txt  a009.txt
a002.txt  a004.txt  a006.txt  a008.txt  a010.txt

$ ./large_f.sh 
Input Directory (Blank is Cancel.) : 1

$ ls 1
A001.TXT  A003.TXT  A005.TXT  A007.TXT  A009.TXT
A002.TXT  A004.TXT  A006.TXT  A008.TXT  A010.TXT