Commit | Line | Data |
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e6817382 BJ |
1 | .TH CRON 8 |
2 | .SH NAME | |
3 | cron \- clock daemon | |
4 | .SH SYNOPSIS | |
5 | .B /etc/cron | |
6 | .SH DESCRIPTION | |
7 | .I Cron | |
8 | executes commands at specified dates and times | |
9 | according to the instructions in the file | |
10 | /usr/lib/crontab. | |
11 | Since | |
12 | .I cron | |
13 | never exits, | |
14 | it should only be executed once. | |
15 | This is best done by running | |
16 | .I cron | |
17 | from the initialization | |
18 | process through the file | |
19 | /etc/rc; | |
20 | see | |
21 | .IR init (8). | |
22 | .PP | |
23 | Crontab | |
24 | consists of lines of six fields each. | |
25 | The fields are separated by spaces or tabs. | |
26 | The first five are integer patterns to | |
27 | specify the | |
28 | minute (0-59), | |
29 | hour (0-23), | |
30 | day of the month (1-31), | |
31 | month of the year (1-12), | |
32 | and day of the week (1-7 with 1=monday). | |
33 | Each of these patterns may | |
34 | contain a number in the range above; | |
35 | two numbers separated by | |
36 | a minus | |
37 | meaning a range inclusive; | |
38 | a list of numbers separated by | |
39 | commas meaning any of the numbers; | |
40 | or an asterisk meaning all legal values. | |
41 | The sixth field is a string | |
42 | that is executed by the Shell at the | |
43 | specified times. | |
44 | A percent character | |
45 | in this field is translated to a new-line | |
46 | character. | |
47 | Only the first line (up to a % or end of line) | |
48 | of the command field is executed by the Shell. | |
49 | The other lines are made available to the | |
50 | command as standard input. | |
51 | .PP | |
52 | Crontab is examined by | |
53 | .I cron | |
54 | every minute. | |
55 | .SH FILES | |
56 | /usr/lib/crontab |