Cronie follows the standard Vixie-cron behavior where a specified day-of-month and day-of-week are treated as alogicalOR. This means a job runs if either condition is met.

It would be very useful to have a pattern-specific way to switch this to alogicalAND. This would allow for schedules like "run on the 1st of the month only if it is also a Monday."

I've started an effort to make a detailed specification for existing and new features of cron, TheOCPS-project.

In increment 1.4 (draft), I've added a section on this, looking something like:

4.1.2. Explicit AND Logic (+ Modifier)

To provide a portable, unambiguous method for requiring both date conditions to be met, OCPS 1.4 introduces the+ (plus) modifier.

• Functionality: When the+ character precedes the value in theDay of Week field, the logical combination for that specific pattern MUST be treated as a logicalAND.
• Syntax:
  • The+ modifier is ONLY valid as the first character of theDay of Week field.
  • Its use in any other field or position MUST be treated as a parsing error.
• Example (0 12 1 * +MON):
  • Default (OR)0 12 1 * MON: Triggers at noon on the 1st of the monthOR at noon on every Monday.
  • With+ Modifier0 12 1 * +MON: Triggers at noonONLY IF the 1st of the month is also a Monday.

+ is suggested over other alternatives like& and! for safety and clarity:& is a shell command modifier, and! commonly means NOT.

What do you think about this, could it be implemented in cronie?