7.4: How do I set up cron?
Description
This article is from the Apple II GNO FAQ, by Devin Reade with numerous contributions by others.
7.4: How do I set up cron?
A#7.4: There are man pages for this that were distributed with the v2.0.4
GNO update, but they don't quite match the implementation provided
with the Multi-user 2.0 package.
To activate cron, you must uncomment its entry in the /etc/inittab
file. See the init(8) man page for the format of this file.
Cron is controlled through the /etc/crontab file. Unlike its UNIX
counterparts, the GNO cron does not support setting of environment
variables in the crontab file. These would be lines of the form:
SHELL=/bin/sh
MAILTO=gdr
Any line which begins with a hash (#) character is considered
to be a comment and is ignored.
All other lines in this file are expected to have five space-
delimited date/time fields, followed by a user name field, followed
by a command. The first five fields are:
minute (0-59)
hour (0-23)
day of month (1-31)
month (0-11)
day of week (0-6) (appears to be ignored)
Multiple values may be specified either separated by commas,
or as a range separated with a hyphen.
Following the five date/time fields is a username field.
Although it has to be present, it does not appear to be used
by the current cron implementation.
The last field is the command to be executed at the specified
time. Unlike UNIX cron implementations, these commands _are_not_
executed from a subshell, so meta characters and file redirection
cannot be used.
You cannot split cron commands into separate lines of the crontab
file. Any '%'s in the command are replaced by newlines. Unlike
UNIX crons, the text appearing after a '%' character _is_not_
piped to the input of the command.
BUG WARNING: Do not use more than 10 multiple values in each
of the date-time fields; if there are more than
10, cron's memory structures are reported to get
corrupted.
Continue to:
My Books
