#!/bin/bash
#
# Shell script to rename given file names to from uppercase to
# lowercase OR lowercase to uppercase
FILES="$1"
ME="$(basename $0)"
# function to display message and exit with given exit code
function die(){
echo -e "$1"
exit $2
}
# exit if no command line argument given
[ "$FILES" == "" ] && die "Syntax: $ME {file-name}\nExamples:\n $ME xyz\n $ME \"*.jpg\"" 1 || :
# scan for all input file
for i in $FILES
do
# see if upper to lower OR lower to upper by command name
[ "$ME" == "2upper" ] && N="$(echo "$i" | tr [a-z] [A-Z])" ||  N="$(echo "$i" | tr [A-Z] [a-z])"
# if source and dest file not the same then rename it
[ "$i" != "$N" ] &&  mv "$i" "$N" || :
done