Which crontab special string is equivalent to the time specification `0 0 * * 0`?
LPIC-1 Exam 102-500, objective 107. Administrative tasks easy
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How these questions are written — where each question comes from, what the verification ledger records, and what happens when one is found wrong.
The options
Correct @weekly
Correct. @weekly means midnight on Sunday, which is exactly minute 0, hour 0, any day of month, any month, day of week 0.
Not correct @daily
Wrong. @daily (also spelled @midnight) is `0 0 * * *`, so it runs every night rather than only on Sundays.
Not correct @monthly
Wrong. @monthly is `0 0 1 * *`: midnight on the first day of each month.
Not correct @reboot
Wrong. @reboot has no calendar meaning at all; it runs the command once each time the cron daemon starts up, which in practice means at boot.
Why
Instead of five time fields a crontab entry may start with one of @reboot, @yearly (@annually), @monthly, @weekly, @daily (@midnight) or @hourly. All except @reboot are pure shorthand for a five-field specification. Note that the day-of-week field accepts both 0 and 7 for Sunday.
Where this comes from
- Cited
- manual page crontab(5)
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 107 and space the ones you get wrong.
More questions on this objective
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