For reminding, after smooth install of RDBMS 8.1.7 (cf my previous post)
I read this

:
*Getting an error message saying "can't find class java/lang/Thread"
*You have JDK 1.1.6v5 and not the JRE 1.1.6v5. Java classes are stored in rt.jar in the JRE, while they are stored in classes.zip in the JDK. Furthermore, dbassist has the its -classpath command-line argument set to rt.jar.

See Obtain the Java Runtime Environment
So I tilted that I should have installed JRE1.1.6 tar !
Then I do it in /usr/local. Linked it to /usr/local/jre.
I also edited $ORACLE_HOME/bin/netca :
modified JREDIR to : JREDIR=/usr/local/jre
Do the same with ?bin/dbassist.
Then both should work.
IMPORTANT WARNING:
After that, Oracle linking is ok, all execs seem to work, but oracle binary is still in error (just try with your init.ora, setup your env, and try to connect internal, then startup nomount : Oracle stucks still).
Indeed one last thing is missing : it is GLIBC 2.1.
cf §3.4 of
http://www.mandrakeuser.org/docs/uti...le3.html#ss3.1
And follow exactly what it is in the paragraph.
(download it at kernel.org : cf
http://www.mandrakeuser.org/docs/utils/uoracle2.html)
Now re-install all RDBMS to start from clean.
Patch netca and dbassist after installation.
Tested by myself (newbie in Oracle with Linux :-) ).
So I almost follow the entire advice of mandrakeuser.org's directives... yes indeed. But as I trust nothing and as now I am installing 8.17 (not 8.1.6) on MDK9.0 (not 8.1), quite natural I re-test each part...
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Humm

now the score : 4 install attempts, 3 days research, hope everything is ok now