Rename files within a directory to random strings (don't forget to chmod 755 to execute)

random_rename_files_in_directory.sh

#!/bin/bash

chars=( {a..z} {A..Z} {0..9} )

function rand_string {
    local c=$1 ret=
    while((c--)); do
        ret+=${chars[$((RANDOM%${#chars[@]}))]}
    done
    printf '%s\n' "$ret"
}

for file in ~/PictureDir*
do
    ext=$(echo ${file} | sed 's,^.*\(\.[^\.]*$\),\1,')
    mv "$file" ~PicturesDirRenamed/"$(rand_string 10)"${ext}
done