| 1 | #
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| 2 | # Python Cron
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| 3 | # by Emilio Schapira
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| 4 | # Copyright (C) 2003 Advanced Interface Technologies, Inc.
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| 5 | # http://www.advancedinterfaces.com
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| 6 | # http://sourceforge.net/projects/pycron/
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| 7 | #
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| 8 |
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| 9 | **
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| 10 | ** INTRODUCTION
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| 11 | **
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| 12 |
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| 13 | This is a clone of the well-known cron job scheduler for the unix flavored
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| 14 | operating systems. It is implemented in Python. The main motivation for the
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| 15 | project is to provide a robust cron daemon for the Microsoft Windows*
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| 16 | operating system. However, Python Cron is platform-independant, and can
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| 17 | be used on any operating system that supports python.
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| 18 |
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| 19 | CygWin (http://www.cygwin.com/) provides a robust implementation of the cron
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| 20 | daemon, however it requires installing the full cygwin package. There are
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| 21 | currently other alternatives that are either not robust, not free or not
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| 22 | open source. Examples of these alternatives are WinCron
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| 23 | (http://www.wincron.co.uk/), Cron (http://www.kalab.com/freeware/cron/cron.htm).
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| 24 |
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| 25 | This implementation is very simple, complete and robust.
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| 26 |
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| 27 | **
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| 28 | ** USAGE
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| 29 | **
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| 30 |
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| 31 | usage: cron [crontab_file_name [log_file_name [pid_file_name]]]
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| 32 |
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| 33 | crontab_file_name Name and location of the crontab file. By
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| 34 | default it is ./crontab
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| 35 | log_file_name Name and location of the log file. By default
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| 36 | it is ./cron.log
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| 37 | pid_file_name Name and location of the pid file. This file
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| 38 | will contain the process id of the cron
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| 39 | process. It can be used later to stop the cron
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| 40 | file. By default it is ./cron.pid
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| 41 |
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| 42 | **
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| 43 | ** Crontab files
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| 44 | **
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| 45 |
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| 46 | A contrab file contains one command per line, except empty lines and
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| 47 | lines starting with the character #, which are considered as comments.
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| 48 | This file will be scanned every minute when cron is running.
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| 49 |
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| 50 | Each command has the format:
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| 51 |
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| 52 | <minute> <hour> <day of month> <month> <day of week> <command> <args>
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| 53 |
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| 54 | Cron will scan each entry and match the first five values with the
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| 55 | current local time and date. The entries for each of these values must
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| 56 | be either:
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| 57 |
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| 58 | - A number. For <month> it is the month number, and for <day of week>
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| 59 | is the day number starting with Sunday=0.
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| 60 | - An asterisk (*) which indicates that any value matches this field.
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| 61 | - Comma separated numbers that indicate that each of the values can
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| 62 | match this field.
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| 63 |
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| 64 | The 6th argument, <command>, is the name of the program to run. The remaining
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| 65 | arguments are passed to the programm <command> as command-line arguments.
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| 66 |
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| 67 | Example cron entries
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| 68 |
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| 69 | 0 * * * * echo "run every hour"
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| 70 |
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| 71 | 0 3 * * * echo "run every day at 3am"
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| 72 |
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| 73 | 30,0 * * * * echo "run every half hour"
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| 74 |
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| 75 | 45 15 * * 1 echo "run every monday at 3:45pm"
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| 76 |
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| 77 | 0 4 15 * * echo "run on the 15th of every month at 4am"
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| 78 |
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| 79 | **
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| 80 | ** Windows
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| 81 | **
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| 82 |
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| 83 | This example is for Windows 2K.
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| 84 |
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| 85 | 1.- Unzip the package in c:\Program Files\pycron.
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| 86 |
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| 87 | 2.- You can create a shorcut in the startup folder, with
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| 88 | the following properties:
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| 89 |
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| 90 | Target = C:\Program Files\Python22\pythonw.exe C:\Program Files\pycron\cron.py
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| 91 | Start In = C:\Program Files\pycron
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| 92 |
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| 93 | You will notice that console processes are launched in a new console window.
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| 94 | To avoid this, use the provided program silentstart in your crontab file. For
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| 95 | example:
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| 96 |
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| 97 | # Run backup script every morning at 3am
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| 98 | 0 3 * * * silentstart c:\scripts\backup.bat
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| 99 |
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| 100 | silentstart.exe must be in the path. You can copy it to c:\winnt\system32.
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| 101 |
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| 102 | **
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| 103 | ** Limitations
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| 104 | **
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| 105 |
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| 106 | - Crontab files can not have environment variable definitions.
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| 107 | - pycron doeas not support the expresions of the form /2, month
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| 108 | or day of the week names, or dash expresions such as 5-9.
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| 109 |
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