Installation the Java Runtime Environment (JRE) on Red Hat Enterprise Linux

Question

Hi gurus,
I´m trying to install an ECC 6.0 SR3 (ABAP) on RHEL v.5 with Oracle DB.
But as I am newbie I have some doubts, in this point is with the Java Version JRE that is required in sap installion process.
I already installed the JRE through RPM Package File (I followed the instructions/steps described in this url -  http://java.sun.com/j2se/1.4.2/jre/install-linux.html ) and I don´t have any problem... by the way I installed the JRE version 1.4.2_25 b02.
But after the installation I had a question, how do I check if the package was installed correctly? I insert the commad  java -version, and the result was this:
java version "1.4.2"
gij (GNU libgcj) version 4.1.2 20080704 (Red Hat 4.1.2-46)
Copyright (C) 2006 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
With this information I really do not know if the version 25 was installed...
I already check if there is some directory with the new file, and actually there exist in the directory /usr/java but this is not tell me if this is the new one!!
It´s possible to know which one is installed with other command by terminal?
Best regards,
Joao Dimas - Portugal

Answer 1

1- Ok Markus, but for me it is strange how I could know that the JDK was wrong, that because I don´t know why I have to install this component  for IBM JDK ...... This server has a x86_64 bit architecture, where is related to IBM? I did not understood that sorry... and the component that is installed is 1.4.2 JDK with last version which is 25 to x64 bit (for my x86_64 architecture) ... Forgive my ignorance here, but I don´t understand Markus! Where there is a relationship with the AMD64 architecture? If you are correct... if this is a AMD64 therefore I have to download new installation media DVD´s for this installation for AMD64 architecture, isn´t it?  Because all the dvd's that I have here to install this system is refer to the version x86_64!
X86_64 == AMD64 == x64 see
http://en.wikipedia.org/wiki/X86-64
This is all the same. AMD invented the "64bit extension" for their x86 CPUs, later Intel licensed that extension. All those terms are synonyms.
So if
java -version
does not give you the IBM JDK your installation will fail.
If you check the PAM (http://service.sap.com/pam) you'll see that for 64bit Linux (AMD64, x86_64, x64) only the IBM JDK is supported because Sun has no 64bit JDK for this (ancient) version 1.4.2 for Linux x86_64.
[root@redhatsap IM_LINUX_X86_64]# swapon -s
> Filename                                Type            Size    Used    Priority
> /dev/mapper/VolGroup01-LogVol01         partition       5931000 0       -1
This means that I have about 5,9 Gb of RAM memory?
That means that you have 5,9 GB of SWAP. You get your total memory using the command "free" or use the command "top".
If I need to allocate more memory, as sap recommends 2xRAM, with 8 GB of RAM, how can I do that, in installation guide it tell me to go read the manual for linux... what documentation?!
Honestly, this here is not the place to learn Linux.
I'd use e. g. Google and enter "Redhat 5 add swap space"
http://centos.org/docs/5/html/Deployment_Guide-en-US/s1-swap-adding.html
(btw: CentOS is a RedHat clone, it's the same software and so the same commands).
Markus