Clone github's repositories found on https://github.com/github/dmca before takedown by DMCA.
crontab -e
And put
42 */6 * * * <path_to_github_backup>/github_backup.sh
Example :
42 */6 * * * /home/user/github_backup/github_backup.sh
Every 6 hours github_backup.sh will update dmca's local repository and backup new repositories found.