When programs such as the JRE are installed, it is common to create such symbolic links to them to provide a unique, unchanging location that can be put in the PATH statement, so that the PATH statement does not have to be modified if the program's location is subsequently changed: All that is necessary is to change the symbolic link (see below). If the "locate" program does not give any response at all, then the JRE is almost certainly not installed on your system, although there are also other ways to check this (see below).The "locate" program might also give a different type of response, such as " /usr/bin/java, in which case it is necessary to determine whether this is the actual location of the JRE or merely a "symbolic link" (shortcut) to it. If the "locate" program responds with something like " /usr/java/jre1.5.0_06/bin/java", then the JRE is almost certainly installed on your system, and all that remains is to check whether it is present in your PATH variable (see below). (If the "locate" program is not installed, then skip ahead and try using the "rpm" program: See below.) If the "locate" program is installed, then type: If the "which" program responds with something like " /usr/bin/locate", then the "locate" program is installed. To check whether you have the " locate" program, first open an interactive shell (terminal window or console or X-term, etc.), and type: Checking whether the JRE is Installed Using the " locate" Program One of the easiest ways is to use the program called "locate". There are several possible ways to check whether the Java Runtine Environment is installed on a Linux/Unix computer, depending on how the JRE was installed (if it actually was installed, that is) and what other programs are available to find installed programs. Editing the PATH Statement in Login Files.Adding the JRE to the PATH Statement in Login Files.The following discussion is broken down into eight steps: This article will not cover the javac compiler, nor will it cover any operating systems other than Linux/Unix.
This article explains how to check whether the Java Runtime Environment (JRE) is installed on a Linux/Unix system, and if it is not installed, how to get it, install it, and configure it. JRE on Linux Java Runtime Environment (JRE) on Linux/Unix