[root@aluno09 ~]# cat /etc/issue
Red Hat Enterprise Linux ES release 4 (Nahant Update 4)
Kernel r on an m

criar o usuario oracle, tem que se logar como root:

groupadd oinstall
groupadd dba
groupadd oper

Crie o usuario oracle:

useradd -g oinstall -G dba,oper -d /home/oracle oracle

troque a senha do oracle

passwd oracle

Adicionar essa configuracao ao arquivo /etc/sysctl.conf, ao finalizar digite: sysctl -p
Para confirmar as alteracoes sem precisar de boot,

# Oracle Configurations
kernel.sem = 256 32000 100 128
kernel.shmall = 2097152
kernel.shmmax = 536870912
kernel.shmmni = 4096
kernel.msgmax = 8192
kernel.msgmnb = 65535
kernel.msgmni = 2878
fs.file-max = 65536
net.ipv4.ip_local_port_range = 1024 65000
net.core.rmem_default = 262144
net.core.wmem_default = 262144
net.core.rmem_max = 262144
net.core.wmem_max = 262144
# End Oracle Configurations

Crie um arquivo .bash_profile para o seu usuario com o conteudo abaixo:

vi /home/oracle/.bash_profile

################################################## ACRESCENTAR ao .bash_profile
umask 022

LD_LIBRARY_PATH=/usr/lib:/usr/X11R6/lib
ORACLE_BASE=/u01/app/oracle
ORACLE_HOME=$ORACLE_BASE/product/10.2.0/db_1
ORACLE_SID=orcl
PATH=$ORACLE_HOME/jdk/jre/lib/i386/server:$ORACLE_HOME/rdbms/lib:$ORACLE_HOME/lib:$LD_LIBRARY_PATH:$PATH
PATH=$ORACLE_HOME/bin:$PATH

export PATH LD_LIBRARY_PATH
export ORACLE_BASE ORACLE_HOME ORACLE_SID
unset USERNAME

################################################## TERMINO .bash_profile