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1.1 ! root 1: .\" @(#)cron.8 6.5 (Berkeley) 5/16/86 ! 2: .\" ! 3: .TH CRON 8 "May 16, 1986" ! 4: .AT 3 ! 5: .SH NAME ! 6: cron \- clock daemon ! 7: .SH SYNOPSIS ! 8: .B /etc/cron ! 9: .SH DESCRIPTION ! 10: .I Cron ! 11: executes commands at specified dates and times ! 12: according to the instructions in the files ! 13: /usr/lib/crontab and /usr/lib/crontab.local. ! 14: None, either one, or both of these files may be present. ! 15: Since ! 16: .I cron ! 17: never exits, ! 18: it should only be executed once. ! 19: This is best done by running ! 20: .I cron ! 21: from the initialization ! 22: process through the file ! 23: /etc/rc; ! 24: see ! 25: .IR init (8). ! 26: .PP ! 27: The ! 28: crontab files ! 29: consist of lines of seven fields each. ! 30: The fields are separated by spaces or tabs. ! 31: The first five are integer patterns to specify: ! 32: .in +2m ! 33: .TP 2m ! 34: \(bu ! 35: minute (0-59) ! 36: .nr .0 \n()Pu ! 37: .nr )P 0 ! 38: .TP 2m ! 39: \(bu ! 40: hour (0-23) ! 41: .TP 2m ! 42: \(bu ! 43: day of the month (1-31) ! 44: .TP 2m ! 45: \(bu ! 46: month of the year (1-12) ! 47: .TP 2m ! 48: \(bu ! 49: day of the week (1-7 with 1 = Monday) ! 50: .nr )P \n(.0u ! 51: .in -2m ! 52: .LP ! 53: Each of these patterns may contain: ! 54: .in +2m ! 55: .TP 2m ! 56: \(bu ! 57: a number in the range above ! 58: .nr .0 \n()Pu ! 59: .nr )P 0 ! 60: .TP 2m ! 61: \(bu ! 62: two numbers separated by a minus ! 63: meaning a range inclusive ! 64: .TP 2m ! 65: \(bu ! 66: a list of numbers separated by ! 67: commas meaning any of the numbers ! 68: .TP 2m ! 69: \(bu ! 70: an asterisk meaning all legal values ! 71: .nr )P \n(.0u ! 72: .in -2m ! 73: .LP ! 74: The sixth field is a user name: the ! 75: command will be run with that user's uid and permissions. ! 76: The seventh field consists of all the text ! 77: on a line following the sixth field, ! 78: including spaces and tabs; ! 79: this text is treated as a command ! 80: which is executed by the Shell at the ! 81: specified times. ! 82: A percent character (``%'') ! 83: in this field is translated to a new-line ! 84: character. ! 85: .PP ! 86: Both ! 87: crontab files are checked by ! 88: .I cron ! 89: every minute, on the minute. ! 90: .SH FILES ! 91: /usr/lib/crontab ! 92: .br ! 93: /usr/lib/crontab.local
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