Datasheet

“main” (Installation and Administration) — 2004/6/25 — 13:29 — page 246 — #272

10.2.2 cron Package

The cron tables are now located in /var/cron/tabs. /etc/crontab

serves as a system-wide cron table. Enter the name of the user who should

run the command directly after the time table (see Example 10.1, here root

is entered). Package-speciﬁc tables, located in /etc/cron.d, have the

same format. See man cron.

Example 10.1: Example of an Entry in /etc/crontab

1-59/5 * * * * root test -x /usr/sbin/atrun && /usr/sbin/atrun

/etc/crontab cannot be processed with crontab -e. It must be loaded

directly into an editor, modiﬁed, then saved.

A number of packages install shell scripts to the directories /etc/cron.

hourly, /etc/cron.daily, /etc/cron.weekly, and /etc/cron.

monthly, whose instructions are controlled by /usr/lib/cron/run-

crons. /usr/lib/cron/run-crons is run every ﬁfteen minutes from

the main table (/etc/crontab). This guarantees that processes that may

have been neglected can be run at the proper time.

The daily system maintenance jobs have been distributed to various scripts

for reasons of clarity. Along with aaa_base, /etc/cron.daily contains,

for instance, the components backup-rpmdb, clean-tmp, or clean-vi.

10.2.3 Log Files: Package logrotate

There are a number of system services (daemons), which, along with the

kernel itself, regularly record the system status and speciﬁc events to log

ﬁles. This way, the administrator can regularly check the status of the sys-

tem at a certain point in time, recognize errors or faulty functions, and

troubleshoot them with pinpoint precision. These log ﬁles are normally

stored in /var/log as speciﬁed by FHS and grow on a daily basis. The

logrotate package helps control the growth of these ﬁles.

246 10.2. Hints on Special Software Packages