Your crontab can be stored in any file you choose. For example, you may wish to create or upload a file called cronjobs in
your Virtual Private Server home directory for your crontab. Each line in your crontab will either be an environment variable
setting, a cron table entry, or a comment (beginning with the # symbol).
An environment variable setting in a crontab looks like this:
NAME = VALUE
The cron environment variables include SHELL, LOGNAME, USER, and HOME. In addition to these, there is a special MAILTO environment
variable. Any output generated by your cron jobs will be sent to the address specified by MAILTO (if it is not specified it will be
sent to the owner of the crontab). If MAILTO is defined as an empty string then no mail will be sent.
MAILTO = ""
The format of a cron table entry includes five (5) time fields followed by a command. Commands are executed when the time
specified by the date fields matches the current time. The five time fields are as follows:
Field Allowed Values
Day of Month 1-31
Month 1-12, jan, feb, mar, apr, may, jun, jul, aug, sep, oct,
Day of Week 0-7, sun, mon, tue, wed, thu, fri, sat (0 and 7 are "sun")
A field may be an asterisk (*), which indicates all values in the range are acceptable. Ranges of numbers are allowed, i.e.
2-5 or 8-11, and lists of numbers are allowed, i.e. 1,3,5 or 1,3,8-11. Step values can be represented as
a sequence, i.e. 0-59/15, 1-31/3, or */2.
The actual command you wish to execute, including any parameters to be passed to it, is the sixth, and final field of a cron table
NOTE: Each crontab entry must have a trailing line break in order for the cron table entry to be recognized.
Because of this, you may want to hit Enter a few times at the end of your crontab file when you are editing
Some examples of complete cron table entries are show below, implementing the
vnukelog command as an example.
# Any output generated by the cron entries below is sent to the e-mail
# address assigned to the MAILTO environment variable.
# Execute the "vnukelog" command at 1:15 (15 1) AM every day.
15 1 * * * /usr/local/bin/vnukelog
# Execute the "vnukelog" command at 11:40 PM (40 23) on the first day (1)
# of each month.
40 23 1 * * /usr/local/bin/vnukelog
# Execute the "vnukelog" command every 10 minutes for for the first
# half-hour (0-30/10) of the 9:00 AM and 5:00 PM hours (9,17) on
# Monday-Friday (1-5).
0-30/10 9,17 * * 1-5 /usr/local/bin/vnukelog
# Execute the "vnukelog" command at 4:00 AM, 8:00 AM, 12:00 noon, 4:00 PM,
# and 8:00 PM (0 */4) on each Sunday (sun) every January (jan).
0 */4 * jan sun /usr/local/bin/vnukelog
# Execute the "vnukelog" command at 4:30 AM (30 4) on the first, fifteenth
# (1,15), and each Friday (fri) of every month.
30 4 1,15 * fri /usr/local/bin/vnukelog
# Execute the "vnukelog" command at 12:00 midnight (0 0) on August 19 (8)
0 0 19 8 * /usr/local/bin/vnukelog
0 0 19 aug * /usr/local/bin/vnukelog