This installation is same for all rpm based systems like (Centos/Fedora/RHEL/SLES/Opensuse/Mandriva..)
This tutorial is about 11.2 version client, but should work even for 12.1 version.
Packages are:
oracle-instantclient11.2-basic-11.2.0.4.0-1.x86_64.rpm oracle-instantclient11.2-sqlplus-11.2.0.4.0-1.x86_64.rpm oracle-instantclient11.2-devel-11.2.0.4.0-1.x86_64.rpm
In the future, i will include a post with how to download these packages.
1. Oracle Client Installation
Go to Downloaded rpm packages directory and install them with root privileges.
[[email protected] ~]# yum localinstall oracle* --nogpgcheck ---> Package oracle-instantclient11.2-basic.x86_64 0:11.2.0.4.0-1 set to be updated ---> Package oracle-instantclient11.2-devel.x86_64 0:11.2.0.4.0-1 set to be updated ---> Package oracle-instantclient11.2-sqlplus.x86_64 0:11.2.0.4.0-1 set to be updated --> Finished Dependency Resolution Dependencies Resolved ======================================================================================================================================================================================== Package                                          Arch                   Version                        Repository                                                             Size ======================================================================================================================================================================================== Installing: oracle-instantclient11.2-basic                   x86_64                 11.2.0.4.0-1                   /oracle-instantclient11.2-basic-11.2.0.4.0-1.x86_64                   179 M oracle-instantclient11.2-devel                   x86_64                 11.2.0.4.0-1                   /oracle-instantclient11.2-devel-11.2.0.4.0-1.x86_64                   1.9 M oracle-instantclient11.2-sqlplus                 x86_64                 11.2.0.4.0-1                   /oracle-instantclient11.2-sqlplus-11.2.0.4.0-1.x86_64                 2.8 M Transaction Summary ======================================================================================================================================================================================== Install      3 Package(s) Upgrade      0 Package(s) Total size: 184 M Is this ok [y/N]: y
2. Configure TNSNames.ora
tnsnames.ora file is used to store database connection information. This file must be created and configured in your current client installation.
To do this, first create your network/admin directory
[[email protected] ~]# mkdir /usr/lib/oracle/11.2/client64/network/admin -p
Now inside you can make your tnsnames.ora file.
3. Configure Environment Variables
Create file /etc/profile.d/client.sh with the following file content
 export ORACLE_HOME=/usr/lib/oracle/11.2/client64  export PATH=$PATH:$ORACLE_HOME/bin  export LD_LIBRARY_PATH=$ORACLE_HOME/lib  export TNS_ADMIN=$ORACLE_HOME/network/admin
Now,
1) logout and logon again.
2) Then, run:
sh /etc/profile.d/client.sh
4. Test Installation
To test if Oracle Client and tnsnames.ora works properly execute the following command:
[[email protected] ~]# sqlplus [email protected]_TNSNAMNE.ORA
Done!