crontab - scheduling a shell script (for oracle export)

Cron is a time-based job scheduler in Unix-like computer operating systems. 'cron' is short for Chronograph. Cron enables users to schedule jobs (commands or shell scripts) to run automatically at a certain time or date.

> connected with oracle user.
[oracle@oraclelinux bin]$ pwd
/bin

crontab -e - opens the user's crontab file for viewing/editing

crontab -l - simply lists the crontab file's contents for the user. Think of it as a "cat" function for the crontab.

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[oracle@oraclelinux bin]$ crontab -e

SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=oracle
HOME=/
*/5 * * * * sh /home/oracle/rakesh.sh

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The script will execute every five minute.

http://en.wikipedia.org/wiki/Cron
http://www.crontabrocks.org/

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rakesh.sh shell script :
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#!bin/bash
#PATH=$PATH:$HOME/bin;export PATH
unset USERNAME
#DISPLAY=10.142.200.141:0.0; export DISPLAY
#Oracle Settings
TMP=/tmp; export TMP
TMPDIR=$TMP; export TMPDIR

ORACLE_BASE=/u01/app/oracle; export ORACLE_BASE ORACLE_HOME=/u01/app/oracle/product/10.2.0/db_1; export ORACLE_HOME
ORACLE_SID=jsildb; export ORACLE_SID
ORACLE_HOME_LISTENER=LISTENER; export ORACLE_HOME_LISTENER
ORATAB=/etc/oratab; export ORATAB
#ORACLE_TERM=xterm; export ORACLE_TERM
export PATH=/u01/app/oracle/product/10.2.0/db_1/bin:$PATH
export PATH=/usr/sbin/:$PATH
LD_LIBRARY_PATH=$ORACLE_HOME/lib:lib:usr/lib; export LD_LIBRARY_PATH
CLASSPATH=$ORACLE_HOME/JRE:$ORACLE_HOME/jlib:$ORACLE_HOME/rdbms/jlib; export CLASSPATH
#LD_ASSUME_KERNEL=2.4.1; export LD_ASSUME_KERNEL
export DATE=$(date +"%m_%d_%y_%H:%M:%S_%p")

exp rakesh/rakesh@jsildb file=/home/oracle/erp_backups/rakesh_$DATE.dmp log=/home/oracle/erp_backups/rakesh_$DATE.log statistics=none