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    Creative Commons License
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    Wed, 24 Sep 2014


    /Linux/Debian: Debian Multiarch on amd64

    You will need this for Skype, for example. If you try to install the current version

    skype-debian_4.2.0.11-1_i386.deb

    on a newish 64-bit Debian machine, it will complain about a bunch of missing dependencies. What you need to do:

    dpkg --add-architecture i386
    apt-get update
    dpkg -i /path/to/skype-debian_4.2.0.11-1_i386.deb
    apt-get -f install

    after which a whole pile of *:i386 32-bit packages should install on your 64-bit machine. And skype should start now. But, you may find your sound does not work, as there seems to be a missing dependency. This

    apt-get install libpulse0:i386

    fixed it for me. Further note that you may have to add

    deb http://www.deb-multimedia.org <debian-version> main

    to your /etc/apt/sources.list to find some dependencies that are sometimes not available in vanilla Debian.

    posted at: 20:16 | path: /Linux/Debian | permanent link to this entry

    Tue, 23 Sep 2014


    /Admin/databases/Oracle: Oracle Admin / Client Basics

    Assuming you have an Oracle database running and need to do "stuff" with it, sqlplus[1] is probably the tool (DB client) you are looking for. There are some instructions[2][3] out there for installing an sqlplus client on your Debian desktop, but (so far) I have found making remote connections to an Oracle database to be problematic. It is easiest to run sqlplus on the Oracle machine itself, where sqlplus will always be a part of the install, and configuration is much easier.

    First set up some environment variables required by sqlplus by adding the following to /home/oracle/.bashrc:

    export ORACLE_HOME=/home/oracle/app/oracle/product/12.1.0/dbhome_1/
    export ORACLE_SID=orcl

    These settings are obviously environment-dependent. I believe that orcl is the default name for an Oracle database in a default installation, but per[4] you can find the name(s) of Oracle database(s) configured in /etc/oratab.

    To connect:

    su oracle
    cd /home/oracle/app/oracle/product/12.1.0/dbhome_1/bin
    ./sqlplus "/as sysdba"

    If your background is MySQL, for instance, things now start getting funky. An Oracle "database" is more akin to a MySQL instance. An Oracle "schema" within that "database" is the equivalent, it seems, of a MySQL database. And there is no straight-forward way to get a list of schemas[5][6]. Apparently in Oracle there is a one-to-one relationship between Oracle username and schema. So a list of users is a superset of the list of schemas (since not all users have a schema). These

    SQL> SELECT username FROM dba_users WHERE default_tablespace not in ('SYSTEM','SYSAUX');
    SQL> select distinct owner from dba_objects;

    for instance get you an approximation of such a list of schemas, but produce slightly different results. And this[7]

    SQL> SELECT DISTINCT OWNER, OBJECT_NAME FROM DBA_OBJECTS WHERE OBJECT_TYPE = 'TABLE' AND OWNER = '[some other schema]';

    (godawful!!) query will then show you the list of tables associated with a schema (OWNER parameter above). And

    SQL> describe schema.tablename

    then describes the columns of a table.

    [1] http://docs.oracle.com/cd/E11882_01/server.112/e16604/qstart.htm
    [2] https://www.debian-administration.org/article/430/Oracle_XE_on_Debian
    [3] https://help.ubuntu.com/community/Oracle
    [4] http://www.perlmonks.org/?node_id=520376
    [5] https://stackoverflow.com/questions/4833459/oracle-sql-query-for-listing-all-schemas-in-a-db
    [6] http://datawarehouse.ittoolbox.com/groups/technical-functional/informatica-l/listing-all-schemas-in-oracle-866951
    [7] https://stackoverflow.com/questions/2247310/how-do-i-list-all-tables-in-a-schema-in-oracle-sql

    posted at: 04:44 | path: /Admin/databases/Oracle | permanent link to this entry