[Linux CentOS] "All mirror URLs are not using ftp, http[s] or file." : 오래된 구 os로 취급 받는 centos 6버전..... 어쨌든 해결방법 정리

echo "https://vault.centos.org/6.10/os/x86_64/" > /var/cache/yum/x86_64/6/base/mirrorlist.txt

echo "http://vault.centos.org/6.10/extras/x86_64/" > /var/cache/yum/x86_64/6/extras/mirrorlist.txt

echo "http://vault.centos.org/6.10/updates/x86_64/" > /var/cache/yum/x86_64/6/updates/mirrorlist.txt