Shell 大写转小写

$ cat test
ABC

• ​​convertlowercase.sh​​

#!/usr/bin/env bash

echo -n "Enter File Name: "
read -r file

if [ ! -f "$file" ]; then
        echo "Filename $file does not exists"
        exit 1
fi

tr '[:upper:]' '[:lower:]' < "$file"

执行：

$ bash convertlowercase.sh
Enter File Name: test
abc