$ sudo -s
#
curl -o oracle-database-preinstall-21c-1.0-1.el7.x86_64.rpm https://yum.oracle.com/repo/OracleLinux/OL7/latest/x86_64/getPackage/oracle-database-preinstall-21c-1.0-1.el7.x86_64.rpm
#
yum -y localinstall oracle-database-preinstall-
21c-1.0-1.el7.x86_64.rpm
# yum -y localinstall oracle-database-xe-21c-1.0-1.ol7.x86_64.rpm
$ export ORACLE_SID=XE
$ export ORAENV_ASK=NO
$ . /opt/oracle/product/21c/dbhomeXE/bin/oraenv
ORACLE_HOME = [] ? /opt/oracle/product/21c/dbhomeXEThe Oracle base has been set to /opt/oracle
SQL*Plus: Release 21.0.0.0.0 - Production on Thu Sep 23 08:06:35 2021
Version 21.3.0.0.0
Copyright (c) 1982, 2021, Oracle. All rights reserved.
Enter user-name: sys as sysdba
Enter password:
Conectado a:
Oracle Database 21c Express Edition Release 21.0.0.0.0 - Production
Version 21.3.0.0.0
SQL> show pdbs;
CON_ID CON_NAME OPEN MODE RESTRICTED
---------- ------------------------------ ---------- ----------
2 PDB$SEED READ ONLY NO
3 XEPDB1 READ WRITE NO
SQL>