1CRON(8) System Manager's Manual CRON(8)
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6 cron - clock daemon
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9 /etc/cron
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12 Cron executes commands at specified dates and times according to the
13 instructions in the file /usr/lib/crontab. Since cron never exits, it
14 should only be executed once. This is best done by running cron from
15 the initialization process through the file /etc/rc; see init(8).
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17 Crontab consists of lines of six fields each. The fields are separated
18 by spaces or tabs. The first five are integer patterns to specify the
19 minute (0-59), hour (0-23), day of the month (1-31), month of the year
20 (1-12), and day of the week (1-7 with 1=monday). Each of these pat‐
21 terns may contain a number in the range above; two numbers separated by
22 a minus meaning a range inclusive; a list of numbers separated by com‐
23 mas meaning any of the numbers; or an asterisk meaning all legal val‐
24 ues. The sixth field is a string that is executed by the Shell at the
25 specified times. A percent character in this field is translated to a
26 new-line character. Only the first line (up to a % or end of line) of
27 the command field is executed by the Shell. The other lines are made
28 available to the command as standard input.
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30 Crontab is examined by cron every minute.
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33 /usr/lib/crontab
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37 CRON(8)