Support `@every` to format a schedule at fixed intervals

[photino]

It seems that we have supported predefined schedules like @yearly. Any plan to support @every <duration>?

[zslayton]

@yearly and friends are common (though nonstandard) shortcuts. I don't think I've seen @every in a crontab before. Which implementation(s) support it? Can you point me to some docs?

[photino]

The cron lib in golang has an implementation.