My linux version is centos5.5, kernel version is 2.6.18-194.el5.Install Oracle 11g in linux system preferably 1G memory, 2G of swap space,and at least 4.5G space on hard disk.Follow the steps to install the Oracle 11g .

1.Download Oracle.

Download the corresponding version of the Oracle on Oracle official website.I have downloaded Oracle for linux X86.

http://www.oracle.com/technetwork/database/enterprise-edition/downloads/index.html

2.Create the Oracle user in Linux, and the management group .

Login Linux as root user,and execute the following command:

#/usr/sbin/groupadd dba
#/usr/sbin/groupadd oper
#/usr/sbin/groupadd oinstall
#useradd oracle
#/usr/sbin/usermod -g oinstall -G dba oracle (dba is the management group.)
#/usr/sbin/useradd -g oinstall -G dba oracle
#passwd oracle

Advance create installation directory

#mkdir -p /opt/oracle/product
#mkdir -p /opt/oracle/product/OraHome
#mkdir -p /opt/oraInventory
#mkdir -p /opt/oracle/oradata
#mkdir -p /var/opt/oracle

Sets the group to which the owner belongs, and permissions

#chown -R oracle.oinstall /opt/oracle
#chown -R oracle.oinstall /opt/oracle/oradata
#chown -R oracle.oinstall /opt/oracle/product/OraHome
#chown -R oracle.dba /opt/oraInventory
#chown oracle.dba /var/opt/oracle
#chmod -R 775 /opt/oracle
#chmod -R 755 /var/opt/oracle

Set user Oracle environment variables

#su - oracle
$vim /home/oracle/.bash_profile

In the file, add the following code

export ORACLE_BASE=/opt/oracle
export ORACLE_HOME=$ORACLE_BASE/product/OraHome
export ORACLE_SID=orcl
export ORACLE_OWNER=oracle
export ORACLE_TERM=vt100
export PATH=$PATH:$ORACLE_HOME/bin:$HOME/bin
export PATH=$ORACLE_HOME/bin:$ORACLE_HOME/Apache/Apache/bin:$PATH
LD_LIBRARY_PATH=$ORACLE_HOME/lib:/lib:/usr/lib:/usr/local/lib
export LD_LIBRARY_PATH
CLASSPATH=$ORACLE_HOME/JRE:$ORACLE_HOME/jlib:$ORACLE_HOME/rdbms/jlib
CLASSPATH=$CLASSPATH:$ORACLE_HOME/network/jlib
export CLASSPATH
PATH=$PATH:/usr/sbin; export PATH
PATH=$PATH:/usr/bin; export PATH

Attention

11g:ORA_NLS33=$ORACLE_HOME/nls/admin/data
10g:ORA_NLS33=$ORACLE_HOME/ocommon/nls/admin/data
9i: ORA_NLS33=/oracle/app/ora92/ocommon/nls/admin/data

Save and exit.Execute the following command to let the configuration take effect immediately.

$source $HOME/.bash_profile

3.Extracting Oracle packages

Execute the following command.

#unzip linux_11gR2_database_1of2.zip
#unzip linux_11gR2_database_2of2.zip

Attention to  the extracted directory user  Oracle must have write and execute permissions, you can change user and group of directory to Oracle.

#chown -R oracle database
#chgrp -R oinstall database

4.Install Oracle 11g

Reboot and login as oracle,enter the graphic interface.

#cd database
#./runInstaller

Then enter the graphical installation process ,it is relatively simple, one step at a time, note we install Oracle software first, then configuring the listener and database.Follow the instructions to install the Oracle 11g.

5.Install the listener

Execute command

#netca

Enter the graphical configuration, default directly next to finalize, which you can also modify the monitor name, Protocol, port.
After installation is complete, you can use the command to see if the Listener Configuration is successful.

#ps -ef

6.Install a database program

Execute command

#dbca

Enter the graphical configuration interface and press next until the installation database, and complete.Now the Oracle 11g has successfully installed.



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