Installation guide

the letter "K" run only when the system is changing run levels from a
higher to a lower level. Commands that begin with the letter "S" run in all
cases.
Usually, only commands that begin with the letter "S" are placed in the
rc3.d directory. By default, run level 3 is the highest run level. The
numbering of commands in the /sbin/rc3.d directory is important since
the numbers are sorted and the commands are run in ascending order.
Refer to the rc3
(8) reference page for more information.
4.1.3 Using the crontabs Directory
The crontab command submits a schedule of commands to the cron
system clock daemon. The cron daemon runs shell commands according to
the dates and times specified in the files in the
/var/spool/cron/crontabs directory. Commands that you want to run
on a regular schedule are in these files. Commands that you want to run
only once are in the /var/spool/cron/atjobs/* files and are submitted
with the at command.
The following example of an entry from a file in the
/var/spool/cron/crontabs directory specifies that the runacct
command runs at 2:00 a.m., Monday through Saturday, and output is sent
to the /var/adm/acct/nite/fd2log file:
1 2 3
0 2 * * 1-6 /usr/sbin/acct/runacct > /var/adm/acct/nite/fd2log&
Each entry has the following syntax:
1 Specifies the minutes past the hour, the hour, day of month, month, and
day of week. Note that for the day of week, the value 0 (zero) indicates
Sunday, the value 1 indicates Monday, and so on. You can specify a
single value, more than one value separated by commas, or two values
separated by a dash (
−) to indicate a range of values. You can also
specify an asterisk (*) to indicate no specific value. For example, if an
asterisk (*) is specified for the hour, the command is run every hour.
2 Specifies the command to be executed at the specified time.
3 Specifies, optionally, arguments to the command.
To add a comment to a file, specify a # (number sign) at the beginning of
the line.
The files in the /var/spool/cron/crontabs directory are named for
system users, and the commands in the files are run under the authority of
the user. For example, the commands in the adm file are run under adm
authority.
Customizing the System Environment 4–13