Scheduling backup using Crontab in Linux

Edit the crontab using following command and add the line as below:

$crontab -e

0 06,18 * * * sh /home/oracle/Desktop/bkup.sh

Scheduling backup twice a day at 6 in the morning and 6 in the evening.

Contents of bkup.sh
-------------------
export ORACLE_BASE=/u01/app/oracle
export ORACLE_HOME=$ORACLE_BASE/product/10.1.0/db_1
export PATH=$ORACLE_HOME/bin:$PATH
export ORACLE_SID=edr
mv /home/oracle/edrbkup/old_edr.dmp /home/oracle/edrbkup/old_bkup/
mv /home/oracle/edrbkup/old_edr.log /home/oracle/edrbkup/old_bkup/
mv /home/oracle/edrbkup/edr.dmp /home/oracle/edrbkup/old_edr.dmp
mv /home/oracle/edrbkup/edr.log /home/oracle/edrbkup/old_edr.log
exp edr/regp file=/home/oracle/edrbkup/edr.dmp log=/home/oracle/edrbkup/edr.log owner=edr buffer=200000

This script will automatically clean the old backup and maintains three backups' at any given point of time.

cron commands:

$crontab -l To list the cron jobs scheduled
$crontab -r To remove the cron job
$crontab -e To edit/schedule cron jobs

General Overview:

Crontab Environment

cron invokes the command from the user's HOME directory with the shell, /usr/bin/sh).
cron supplies a default environment for every shell, defining:
HOME=user's-home-directory
LOGNAME=user's-login-id
PATH=/usr/bin:/usr/sbin:.
SHELL=/usr/bin/sh

Users who desire to have their .profile executed must explicitly do so in the crontab entry or in a script called by the entry.


* * * * * command to be executed
- - - - -
| | | | |
| | | | +----- day of week (0 - 6) (sunday = 0)
| | | +------- month (1 - 12)
| | +--------- day of month (1 - 31)
| +----------- hour (0 - 23)
+------------- min (0 - 59)