example shell for batch rename files (change the first 4 char of file name to DRC)

gistfile1.txt

#!/bin/bash

currentDir="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )";
echo "current path is:"$currentDir;


list_alldir(){
for file2 in `ls -a $1`
    do
        if [ x"$file2" != x"." -a x"$file2" != x".." ];then
            if [ -d "$1/$file2" ];then
                echo "$1/$file2"
                # do not rename files in Categories folder
                if [ "$file2" != "Categories" ];then   
                    cd "$1/$file2"
                    for var in `ls`; do
                    if test -f $var
                    then
                        sudo mv -f "$var" `echo "$var" |sed 's/^..../DRC/'`;
                        echo $var edit succeed
                    fi
                    done
                    cd $currentDir
                fi

                list_alldir "$1/$file2"
            fi
        fi
    done
}


list_alldir ./