Hi guys

Java is installed in linux machine and when I enter the command java -version it shows java is not found.
At the same time when i run from the folder where its installed with ./java -version it works.

first of all why its not working from any other place? also why do I need to give ./ from the folder?
Please help me

This deals with basic Linux search paths.

The page here explains it:
http://www.linux-tutorial.info/modul...ent&pageid=329

Redhat EL 5 : if you install a random java package
to /usr/java/ :

cd /usr/bin/
.. example jdk :
# ln -s /usr/java/jdk<version>/jre/bin/java

And if you want a package created for EL 5 :
The Scientific Linux repo .. e.g. i586 :
http://ftp.scientificlinux.org/linux...7-fcs.i586.rpm
> > jdk-1.6.0_17-fcs.i586.rpm
x86_64 : http://ftp.scientificlinux.org/linux...fcs.x86_64.rpm
> > jdk-1.6.0_17-fcs.x86_64.rpm

These packages will set up the links at install ..
also to /etc/alternatives/ ,
so you can change between versions with the command :
# /usr/sbin/update-alternatives --config java
.....

When you encounter a "command not found" message, it does not necessarily mean that the command does not exist... only that it was not found.

You indeed have already verified that the command does exist, when you used cd to go to the directory where you know it to be installed, then used the ./commandname syntax to explicitly refer to it by its location (i.e. "right here").

The shell uses a variable called $PATH to determine "where to look" for a command that you enter. You can see the value of this variable by entering: echo $PATH. The entries in this list are separated by ":" characters.

Offhand, it seems to me that you should work this problem by assuming that, somehow, "the java command didn't get installed in the place where it 'ought to' be." This is not a command-file that should find itself "just any old where," and it I'd suggest that you first try to figure out why it is where it is.