How to register CRON in seconds correctly?

Question

Task Schedulers

There is a job that runs every minute
Sending messages every minute.
* * * * * /usr/bin/php -q /var/www/b2bmails/data/www/b2bmails.ru/apps/console/console.php send-campaigns >/dev/null 2>&
1 the same task that is processed every 20 seconds, for example, and how much is it fraught with load on the server?

Answer 1

and what does the value 2>&1 mean

Answer 2

there is no cron in seconds, in the second script, set
2>&1, which means that the second type of messages should be displayed where the first type
types are - 1) execution and 2) errors

Answer 3

Run the task every 20 seconds
*/1 * * * * root /home/mybin/script.sh; /bin/sleep20; /home/mybin/script.sh /bin/sleep20; /home/mybin/script.sh