#!/bin/bash

checkcommand()
{
    local result
    local command="$1"
    which "$command" 1>/dev/null 2>&1
    if [[ $? == 0 ]]; then
        echo "$command requirement OK"
        result=1
    else
        echo "$command requirement MISSING"
        result=0
    fi
    return $result
}

# main
if [[ "$1" == "-h" ]]; then
    echo "The lowext command lowercases JPG file extensions in the current directory not recursively."
else
    checkcommand rename
    if [[ $? == 1 ]]; then
        uppercaseCount=$(find -maxdepth 1 -name '*.JPG' | wc -l)
        if [[ $uppercaseCount > 0 ]]; then
            rename 's/JPG/jpg/' *.JPG
        fi
        echo ".JPG -> .jpg: $uppercaseCount"
    fi
fi