#!/bin/bash

while IFS= read -r -d '' oldpath; do
    newpath=${oldpath// /_}
  
    if [[ "$oldpath" != "$newpath" && ! -e "$newpath" ]]; then
        mv -- "$oldpath" "$newpath"
        printf '%s' "$newpath" | pbcopy
    fi
done < <(
    find "$HOME/Screenshot" -maxdepth 1 -type f -name 'screenshot *' -print0 | sort -z
)