Where is the JDK on my UNIX or Linux system?

$ which javac

/usr/bin/javac
$ ls -l /usr/bin/javac
lrwxrwxrwx 1 root root 23 2008-09-18 00:47 /usr/bin/javac -> /etc/alternatives/javac
$ ls -l /etc/alternatives/javac
lrwxrwxrwx 1 root root 33 2008-09-18 00:47 /etc/alternatives/javac -> /usr/lib/jvm/java-6-sun/bin/javac
$ ls -l /usr/lib/jvm/java-6-sun/bin/javac
-rwxr-xr-x 1 root root 47744 2008-03-25 10:01 /usr/lib/jvm/java-6-sun/bin/javac

If you are manually searching for the JDK on your UNIX/Linux machine, look in the following directories:

/usr/java
/usr/java/jdk
/usr/j2se
/usr/j2sdk
/usr/jdk
/usr/lib/java
/usr/lib/j2se
/usr/lib/j2sdk
/usr/lib/jdk
/usr/lib/jvm/java
/usr/lib/jvm/j2se
/usr/lib/jvm/j2sdk
/usr/lib/jvm/jdk
/usr/local/java
/usr/local/java/jdk
/usr/local/jdk
/opt/java
/opt/j2se
/opt/j2sdk
/opt/jdk

The rightmost directory name will usually have suffix that indicates the version number and/or platform. There may be a hyphen between the name and version number. The version number may have dots or underscores. For example,

java-6-sun
jdk-1.6.0-sun
jdk1.6.0
jdk-1_5_0_07-linux-i586
j2sdk1_4_2_02

isCOBOL provides a shell script $ISCOBOL/bin/iscc which sets ISCOBOL_JDK_ROOT based on the actual location of the "javac" executable that is in the user's PATH. Here is a snippet of code that you could use in your own shell script to find the location of the JDK:


				#!/bin/sh

_JAVAC_LOCATION=`type javac | cut -f3 -d' '`

while [ -h "$_JAVAC_LOCATION" ]; do
        _LS_OUTPUT=`ls -ld "$_JAVAC_LOCATION"`
        _EXPR_OUTPUT=`expr "$_LS_OUTPUT" : '.*-> (.*)$'`
        if expr "$_EXPR_OUTPUT" : '/.*' > /dev/null; then
                _JAVAC_LOCATION="$_EXPR_OUTPUT"
        else
                _JAVAC_LOCATION=`dirname "$_JAVAC_LOCATION"`/"$_EXPR_OUTPUT"
        fi
done

_JDK_BINDIR=`dirname $_JAVAC_LOCATION`
ISCOBOL_JDK_ROOT=`dirname $_JDK_BINDIR`

if [ ! -f "$ISCOBOL_JDK_ROOT/lib/tools.jar" ]
then
        echo "ERROR: Could not locate the Java compiler classes (tools.jar)."
        echo "Please ensure that ISCOBOL_JDK_ROOT is set correctly"
        exit 1
fi

echo $ISCOBOL_JDK_ROOT