Cron Notes

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I have huge, horrible, complex cron files. I stick this big comment at the top of the /etc/crontab file so I don't have to keep going back to the man page.

# The time and date fields are:
#     field          allowed values
#     -----          --------------
#     minute         0-59
#     hour           0-23
#     day of month   1-31
#     month          1-12 (or names, see below)
#     day of week    0-7 (0 or 7 is Sun, or use names)
# A field may be an asterisk (*), which always stands for ''first-last''.
# 
# Ranges of numbers are allowed. Ranges are two numbers separated with a hyphen.
# The specified range is inclusive. For example, 8-11 for an ''hours'' entry
# specifies execution at hours 8, 9, 10 and 11.
# 
# Lists are allowed.  A list is a set of numbers (or ranges) separated by commas.
# Examples: ''1,2,5,9'', ''0-4,8-12''.
# 
# Step values can be used in conjunction with ranges. Following a range with
# ''/<number>'' specifies  skips of the number's value through the range. 
# For example, ''0-23/2'' can be used in the hours field to specify command
# execution every other hour (the alternative in the V7 standard is
# ''0,2,4,6,8,10,12,14,16,18,20,22''). Steps are also permitted after an
# asterisk, so if you want to say ''every two hours'', just use ''*/2''.
#
# Example cron file
#      # run five minutes after midnight, every day
#      5 0 * * *       $HOME/bin/daily.job >> $HOME/tmp/out 2>&1
#      # run at 2:15pm on the first of every month -- output mailed to paul
#      15 14 1 * *     $HOME/bin/monthly
#      # run at 10 pm on weekdays, annoy Joe
#      0 22 * * 1-5    mail -s "It's 10pm" joe%Joe,%%Where are your kids?%
#      23 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday"
#      5 4 * * sun     echo "run at 5 after 4 every sunday"