THE VIRTUAL SERVER HANDBOOK

% crontab  r

This will remove the Cron entry you have loaded.

Note:  If you created a Cron entry with " crontab  e" and your run

"crontab  r", you will lose your Cron entry forever. This is a good reason

to keep a physical copy of your Cron file and load it into memory.

Creating Cron files

In a Cron file, blank lines are ignored. Lines that have a pound sign (#) as

the first character are considered comments. There are two types of Cron

entries; environmental variables and Cron commands.

Environmental variables

Environmental variables have the form:

name = value

The spaces around the equal sign are optional and any spaces in the "value"

will be included in the value being set. The value string may be placed in

quotes (either single or double) to preserve leading or trailing spaces.

One environmental variable that can be set is the MAILTO variable. If

MAILTO is defined, any mail that is sent by Cron, such as error

notifications, are sent to the address assigned to the variable. If this value is

not explicitly defined, error mail messages will be sent to the Virtual Server

Administrator login name. For example, if your Virtual Server administrator

login name (i.e., Telnet login name) were "judy", administrative e mail

from the Cron daemon would be sent to judy@yourdomain.com. An

example MAILTO entry might look like:

MAILTO=johndoe@somedomain.com

If MAILTO is defined as follows:

MAILTO=""

no mail will be sent from Cron

Setting Cron commands

Each command entry in a Cron file is composed of a series of fields that

Cron uses to determine what event to run at a specific time and date. The

first five fields (space delimited) specify time and date information as

follows:

 CRON Time and Date fields

Field

Allowed values

Minute

0 59

Hour

0 23

Day of Month

0 31

Month

0 12 (first three letters of month names allowed)

Day of Week

0 7 (first three letters of weekday names allowed)

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 1999  DIGITAL TOOLS  LLC.

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