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49 lines
1.5 KiB
Groff
49 lines
1.5 KiB
Groff
CRON(8) UNIX Programmer's Manual CRON(8)
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NAME
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cron - clock daemon
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SYNOPSIS
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/usr/sbin/cron
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DESCRIPTION
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Cron executes commands at specified dates and times accord-
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ing to the instructions in the file /etc/crontab (if it exists).
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Since cron never exits, it should only be executed once. This
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is best done by running cron from the initialization process
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through the file /etc/inittab; see init(8).
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The crontab file consists of lines of seven fields each.
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The fields are separated by spaces or tabs. The first five
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are integer patterns to specify:
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o+ minute (0-59)
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o+ hour (0-23)
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o+ day of the month (1-31)
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o+ month of the year (1-12)
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o+ day of the week (1-7 with 1 = Monday)
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Each of these patterns may contain:
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o+ a number in the range above
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o+ two numbers separated by a minus meaning a range inclusive
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o+ a list of numbers separated by commas meaning any of the
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numbers
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o+ an asterisk meaning all legal values
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The sixth field is a user name: the command will be run with
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that user's uid and permissions. The seventh field consists
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of all the text on a line following the sixth field, includ-
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ing spaces and tabs; this text is treated as a command which
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is executed by the Shell at the specified times. A percent
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character (``%'') in this field is translated to a new-line
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character.
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The crontab file is checked by cron every minute, on the
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minute.
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FILES
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/etc/crontab
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