cron. Is the cronjob added correctly?

Question

Task Schedulers

Hello, the essence of the question is this:
I wanted to add backup scripts to cron, I sketched a file with tasks,
first I executed the crontab -l command under root, it did not display any text,
then I executed the crontab /path/to/file command under root ...
the command executed the contents The file began to be displayed through crontab -l
and so, the question is whether I added the task correctly or did all other cronjobs for root fly off?
then for some reason I also executed the crontab /etc/crontab command, will it incur any consequences, and if so, how to roll back?

Answer 1

bad is the admin who does not make backups