Red Hat ENTERPRISE LINUX WS 2.1 - Guia de Instalação descarregar pdf (Página 226)

226 Important Linux features

DONE

INDEX

13.4.3 cron - crontab

Any Linux command or program can be executed automatically on a regular basis.

check if crond is running: ps -efw| grep crond

if crond is not running: service crond start

create a crontab file using the following syntax:

min hour daymo month daywk command

min: minute (0-59)

hour: hour (0-23)

daymo: day of the month (1-31)

month: month of the year (1-12)

daywk: day of the week (0-6 with 0=Sunday)

command: the command or program to be executed

Suppose you want to:

• backup your data at 4.30 am on Tuesday to Friday

• delete all core files at 2 am on Sunday

Note that the second task needs root permissions.

a) type cd to go to your home directory

b) type su to become root

c) edit the file fila and enter the following lines:

30 04 * * 2-5 tar cv /u/data/<user>/nmr

00 02 * * 0 find / -name core -exec rm {} \;

d) type crontab fila

You can skip step b) if all tasks in your crontab file can be done as normal user.

Type man crontab for more information.

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Red Hat ENTERPRISE LINUX WS 2.1 - Guia de Instalação Página 226