Oracle is one of the top relational databases in the world and has been used by Fortune 500 companies such as Exxon Mobil, Wal-mart, General Electric and many others. In this tutorial, we will show you six "must know" Oracle SQL commands.
Now that you have started Oracle in Ubuntu, the next thing is to login as SYSTEM. The user “SYSTEM” has database administration privileges that have been created during the installation of Oracle in Ubuntu. You should remember the password you assign for “SYSTEM”. To use the “connect” command and login as SYSTEM, type the following into the SQL-plus prompt (after starting Oracle using the startup command):
SQL> connect system Enter password: Connected.
Once you see “connected” you are connected as “system” to Oracle. The following are some common problems relating to the CONNECT command in Oracle:
ORA-01034: ORACLE not available ORA-27121: unable to determine size of shared memory segment Linux Error: 13: Permission denied
ORA-27140: attach to post/wait facility failed
In Linux terminal:
1.) Login as root:
codex-m@codex-m-desktop:~$ sudo -s -H
[sudo] password for codex-m:
2.) Go to root directory:
root@codex-m-desktop:/home/codex-m# cd / root@codex-m-desktop:/#
3.) Go to /usr/lib and list the files/directories under it
root@codex-m-desktop:/# cd usr/lib root@codex-m-desktop:/usr/lib# ls -l -a
Look for “oracle” and make sure it has the following permission and owners: